Distributed Unit Connection Issue

ABSTRACT

A base station central unit may transmit packet data convergence protocol (PDCP) packets of a radio bearer. The base station distributed unit may transmit the PDCP packets to a wireless device via the radio bearer. The base station central unit may receive, from a base station distributed unit, a first message comprising a first data radio bearer identifier of the radio bearer to be released. The first message may initiate a bearer release procedure. The base station central unit may transmit, to the base station distributed unit, a second message confirming release of the radio bearer. The base station central unit may transmit, to the base station distributed unit, a radio resource control message for the wireless device. The radio resource control message may comprise the first data radio bearer identifier. The base station distributed unit may transmit the radio resource control message to the wireless device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/520,952, filed Jun. 16, 2017, U.S. Provisional PatentApplication No. 62/520,943, filed Jun. 16, 2017, U.S. Provisional PatentApplication No. 62/522,263, filed Jun. 20, 2017, and U.S. ProvisionalPatent Application No. 62/522,276, filed Jun. 20, 2017, which are herebyincorporated by reference in their entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers in a carrier group as per an aspect of anembodiment of the present invention.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention.

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present invention.

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present invention.

FIG. 6 is an example diagram for a protocol structure withmulti-connectivity as per an aspect of an embodiment of the presentinvention.

FIG. 7 is an example diagram for a protocol structure with CA and DC asper an aspect of an embodiment of the present invention.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present invention.

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention.

FIG. 10A and FIG. 10B are example diagrams for interfaces between a 5Gcore network (e.g. NGC) and base stations (e.g. gNB and eLTE eNB) as peran aspect of an embodiment of the present invention.

FIG. 11A, FIG. 11B, FIG. 11C, FIG. 11D, FIG. 11E, and FIG. 11F areexample diagrams for architectures of tight interworking between 5G RAN(e.g. gNB) and LTE RAN (e.g. (e)LTE eNB) as per an aspect of anembodiment of the present invention.

FIG. 12A, FIG. 12B, and FIG. 12C are example diagrams for radio protocolstructures of tight interworking bearers as per an aspect of anembodiment of the present invention.

FIG. 13A and FIG. 13B are example diagrams for gNB deployment scenariosas per an aspect of an embodiment of the present invention.

FIG. 14 is an example diagram for functional split option examples ofthe centralized gNB deployment scenario as per an aspect of anembodiment of the present invention.

FIG. 15 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 16 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 17 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 18 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 19 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 20 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 21 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 22 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 23 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 24 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 25 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 26 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 27 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 28 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 29 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 30 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 31 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 32 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 33 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 34 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 35 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 36 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 37 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 38 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 39 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 40 is an example diagram of an aspect of an embodiment of thepresent disclosure.

FIG. 41 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 42 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 43 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 44 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 45 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 46 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 47 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 48 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 49 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 50 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 51 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 52 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

FIG. 53 is a flow diagram of an aspect of an embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enable operation ofwireless communication systems. Embodiments of the technology disclosedherein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to cellular wireless systems in amulticarrier communication systems.

The following Acronyms are used throughout the present disclosure:

-   -   ASIC application-specific integrated circuit    -   BPSK binary phase shift keying    -   CA carrier aggregation    -   CSI channel state information    -   CDMA code division multiple access    -   CSS common search space    -   CPLD complex programmable logic devices    -   CC component carrier    -   CP cyclic prefix    -   DL downlink    -   DCI downlink control information    -   DC dual connectivity    -   eMBB enhanced mobile broadband    -   EPC evolved packet core    -   E-UTRAN evolved-universal terrestrial radio access network    -   FPGA field programmable gate arrays    -   FDD frequency division multiplexing    -   HDL hardware description languages    -   HARQ hybrid automatic repeat request    -   IE information element    -   LTE long term evolution    -   MCG master cell group    -   MeNB master evolved node B    -   MIB master information block    -   MAC media access control    -   MAC media access control    -   MME mobility management entity    -   mMTC massive machine type communications    -   NAS non-access stratum    -   NR new radio    -   OFDM orthogonal frequency division multiplexing    -   PDCP packet data convergence protocol    -   PDU packet data unit    -   PHY physical    -   PDCCH physical downlink control channel    -   PHICH physical HARQ indicator channel    -   PUCCH physical uplink control channel    -   PUSCH physical uplink shared channel    -   PCell primary cell    -   PCell primary cell    -   PCC primary component carrier    -   PSCell primary secondary cell    -   pTAG primary timing advance group    -   QAM quadrature amplitude modulation    -   QPSK quadrature phase shift keying    -   RBG resource block groups    -   RLC radio link control    -   RRC radio resource control    -   RA random access    -   RB resource blocks    -   SCC secondary component carrier    -   SCell secondary cell    -   Scell secondary cells    -   SCG secondary cell group    -   SeNB secondary evolved node B    -   sTAGs secondary timing advance group    -   SDU service data unit    -   S-GW serving gateway    -   SRB signaling radio bearer    -   SC-OFDM single carrier-OFDM    -   SFN system frame number    -   SIB system information block    -   TAI tracking area identifier    -   TAT time alignment timer    -   TDD time division duplexing    -   TDMA time division multiple access    -   TA timing advance    -   TAG timing advance group    -   TTI transmission time intervalTB transport block    -   UL uplink    -   UE user equipment    -   URLLC ultra-reliable low-latency communications    -   VHDL VHSIC hardware description language    -   CU central unit    -   DU distributed unit    -   Fs-C Fs-control plane    -   Fs-U Fs-user plane    -   gNB next generation node B    -   NGC next generation core    -   NG CP next generation control plane core    -   NG-C NG-control plane    -   NG-U NG-user plane    -   NR new radio    -   NR MAC new radio MAC    -   NR PHY new radio physical    -   NR PDCP new radio PDCP    -   NR RLC new radio RLC    -   NR RRC new radio RRC    -   NSSAI network slice selection assistance information    -   PLMN public land mobile network    -   UPGW user plane gateway    -   Xn-C Xn-control plane    -   Xn-U Xn-user plane    -   Xx-C Xx-control plane    -   Xx-U Xx-user plane

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA, OFDM,TDMA, Wavelet technologies, and/or the like. Hybrid transmissionmechanisms such as TDMA/CDMA, and OFDM/CDMA may also be employed.Various modulation schemes may be applied for signal transmission in thephysical layer. Examples of modulation schemes include, but are notlimited to: phase, amplitude, code, a combination of these, and/or thelike. An example radio transmission method may implement QAM using BPSK,QPSK, 16-QAM, 64-QAM, 256-QAM, and/or the like. Physical radiotransmission may be enhanced by dynamically or semi-dynamically changingthe modulation and coding scheme depending on transmission requirementsand radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention. As illustrated in thisexample, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, DFTS-OFDM, SC-OFDM technology, or the like. Forexample, arrow 101 shows a subcarrier transmitting information symbols.FIG. 1 is for illustration purposes, and a typical multicarrier OFDMsystem may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD and TDD duplexmechanisms. FIG. 2 shows an example FDD frame timing. Downlink anduplink transmissions may be organized into radio frames 201. In thisexample, radio frame duration is 10 msec. Other frame durations, forexample, in the range of 1 to 100 msec may also be supported. In thisexample, each 10 ms radio frame 201 may be divided into ten equallysized subframes 202. Other subframe durations such as including 0.5msec, 1 msec, 2 msec, and 5 msec may also be supported. Subframe(s) mayconsist of two or more slots (e.g. slots 206 and 207). For the exampleof FDD, 10 subframes may be available for downlink transmission and 10subframes may be available for uplink transmissions in each 10 msinterval. Uplink and downlink transmissions may be separated in thefrequency domain. A slot may be 7 or 14 OFDM symbols for the samesubcarrier spacing of up to 60 kHz with normal CP. A slot may be 14 OFDMsymbols for the same subcarrier spacing higher than 60 kHz with normalCP. A slot may contain all downlink, all uplink, or a downlink part andan uplink part and/or alike. Slot aggregation may be supported, e.g.,data transmission may be scheduled to span one or multiple slots. In anexample, a mini-slot may start at an OFDM symbol in a subframe. Amini-slot may have a duration of one or more OFDM symbols. Slot(s) mayinclude a plurality of OFDM symbols 203. The number of OFDM symbols 203in a slot 206 may depend on the cyclic prefix length and subcarrierspacing.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or RBs may depend, at least in part, on thedownlink transmission bandwidth 306 configured in the cell. The smallestradio resource unit may be called a resource element (e.g. 301).Resource elements may be grouped into resource blocks (e.g. 302).Resource blocks may be grouped into larger radio resources calledResource Block Groups (RBG) (e.g. 303). The transmitted signal in slot206 may be described by one or several resource grids of a plurality ofsubcarriers and a plurality of OFDM symbols. Resource blocks may be usedto describe the mapping of certain physical channels to resourceelements. Other pre-defined groupings of physical resource elements maybe implemented in the system depending on the radio technology. Forexample, 24 subcarriers may be grouped as a radio block for a durationof 5 msec. In an illustrative example, a resource block may correspondto one slot in the time domain and 180 kHz in the frequency domain (for15 KHz subcarrier bandwidth and 12 subcarriers).

In an example embodiment, multiple numerologies may be supported. In anexample, a numerology may be derived by scaling a basic subcarrierspacing by an integer N. In an example, scalable numerology may allow atleast from 15 kHz to 480 kHz subcarrier spacing. The numerology with 15kHz and scaled numerology with different subcarrier spacing with thesame CP overhead may align at a symbol boundary every 1 ms in a NRcarrier.

FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D are example diagrams for uplinkand downlink signal transmission as per an aspect of an embodiment ofthe present invention. FIG. 5A shows an example uplink physical channel.The baseband signal representing the physical uplink shared channel mayperform the following processes. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments. The functions may comprise scrambling,modulation of scrambled bits to generate complex-valued symbols, mappingof the complex-valued modulation symbols onto one or severaltransmission layers, transform precoding to generate complex-valuedsymbols, precoding of the complex-valued symbols, mapping of precodedcomplex-valued symbols to resource elements, generation ofcomplex-valued time-domain DFTS-OFDM/SC-FDMA signal for each antennaport, and/or the like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued DFTS-OFDM/SC-FDMA baseband signal for each antenna portand/or the complex-valued PRACH baseband signal is shown in FIG. 5B.Filtering may be employed prior to transmission.

An example structure for Downlink Transmissions is shown in FIG. 5C. Thebaseband signal representing a downlink physical channel may perform thefollowing processes. These functions are illustrated as examples and itis anticipated that other mechanisms may be implemented in variousembodiments. The functions include scrambling of coded bits in each ofthe codewords to be transmitted on a physical channel; modulation ofscrambled bits to generate complex-valued modulation symbols; mapping ofthe complex-valued modulation symbols onto one or several transmissionlayers; precoding of the complex-valued modulation symbols on each layerfor transmission on the antenna ports; mapping of complex-valuedmodulation symbols for each antenna port to resource elements;generation of complex-valued time-domain OFDM signal for each antennaport, and/or the like.

Example modulation and up-conversion to the carrier frequency of thecomplex-valued OFDM baseband signal for each antenna port is shown inFIG. 5D. Filtering may be employed prior to transmission.

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present invention.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated are FIG. 1,FIG. 2, FIG. 3, FIG. 5, and associated text.

An interface may be a hardware interface, a firmware interface, asoftware interface, and/or a combination thereof. The hardware interfacemay include connectors, wires, electronic devices such as drivers,amplifiers, and/or the like. A software interface may include codestored in a memory device to implement protocol(s), protocol layers,communication drivers, device drivers, combinations thereof, and/or thelike. A firmware interface may include a combination of embeddedhardware and code stored in and/or in communication with a memory deviceto implement connections, electronic device operations, protocol(s),protocol layers, communication drivers, device drivers, hardwareoperations, combinations thereof, and/or the like.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics inthe device, whether the device is in an operational or non-operationalstate.

According to some of the various aspects of embodiments, a 5G networkmay include a multitude of base stations, providing a user plane NRPDCP/NR RLC/NR MAC/NR PHY and control plane (NR RRC) protocolterminations towards the wireless device. The base station(s) may beinterconnected with other base station(s) (e.g. employing an Xninterface). The base stations may also be connected employing, forexample, an NG interface to an NGC. FIG. 10A and FIG. 10B are examplediagrams for interfaces between a 5G core network (e.g. NGC) and basestations (e.g. gNB and eLTE eNB) as per an aspect of an embodiment ofthe present invention. For example, the base stations may beinterconnected to the NGC control plane (e.g. NG CP) employing the NG-Cinterface and to the NGC user plane (e.g. UPGW) employing the NG-Uinterface. The NG interface may support a many-to-many relation between5G core networks and base stations.

A base station may include many sectors for example: 1, 2, 3, 4, or 6sectors. A base station may include many cells, for example, rangingfrom 1 to 50 cells or more. A cell may be categorized, for example, as aprimary cell or secondary cell. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI), and at RRCconnection re-establishment/handover, one serving cell may provide thesecurity input. This cell may be referred to as the Primary Cell(PCell). In the downlink, the carrier corresponding to the PCell may bethe Downlink Primary Component Carrier (DL PCC), while in the uplink, itmay be the Uplink Primary Component Carrier (UL PCC). Depending onwireless device capabilities, Secondary Cells (SCells) may be configuredto form together with the PCell a set of serving cells. In the downlink,the carrier corresponding to an SCell may be a Downlink SecondaryComponent Carrier (DL SCC), while in the uplink, it may be an UplinkSecondary Component Carrier (UL SCC). An SCell may or may not have anuplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned a physical cell ID and a cell index. A carrier (downlinkor uplink) may belong to only one cell. The cell ID or Cell index mayalso identify the downlink carrier or uplink carrier of the cell(depending on the context it is used). In the specification, cell ID maybe equally referred to a carrier ID, and cell index may be referred tocarrier index. In implementation, the physical cell ID or cell index maybe assigned to a cell. A cell ID may be determined using asynchronization signal transmitted on a downlink carrier. A cell indexmay be determined using RRC messages. For example, when thespecification refers to a first physical cell ID for a first downlinkcarrier, the specification may mean the first physical cell ID is for acell comprising the first downlink carrier. The same concept may applyto, for example, carrier activation. When the specification indicatesthat a first carrier is activated, the specification may equally meanthat the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, variousexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices may support multiple technologies, and/or multiple releases ofthe same technology. Wireless devices may have some specificcapability(ies) depending on its wireless device category and/orcapability(ies). A base station may comprise multiple sectors. When thisdisclosure refers to a base station communicating with a plurality ofwireless devices, this disclosure may refer to a subset of the totalwireless devices in a coverage area. This disclosure may refer to, forexample, a plurality of wireless devices of a given LTE or 5G releasewith a given capability and in a given sector of the base station. Theplurality of wireless devices in this disclosure may refer to a selectedplurality of wireless devices, and/or a subset of total wireless devicesin a coverage area which perform according to disclosed methods, and/orthe like. There may be a plurality of wireless devices in a coveragearea that may not comply with the disclosed methods, for example,because those wireless devices perform based on older releases of LTE or5G technology.

FIG. 6 and FIG. 7 are example diagrams for protocol structure with CAand multi-connectivity as per an aspect of an embodiment of the presentinvention. NR may support multi-connectivity operation whereby amultiple RX/TX UE in RRC_CONNECTED may be configured to utilize radioresources provided by multiple schedulers located in multiple gNBsconnected via a non-ideal or ideal backhaul over the Xn interface. gNBsinvolved in multi-connectivity for a certain UE may assume two differentroles: a gNB may either act as a master gNB or as a secondary gNB. Inmulti-connectivity, a UE may be connected to one master gNB and one ormore secondary gNBs. FIG. 7 illustrates one example structure for the UEside MAC entities when a Master Cell Group (MCG) and a Secondary CellGroup (SCG) are configured, and it may not restrict implementation.Media Broadcast Multicast Service (MBMS) reception is not shown in thisfigure for simplicity.

In multi-connectivity, the radio protocol architecture that a particularbearer uses may depend on how the bearer is setup. Three alternativesmay exist, an MCG bearer, an SCG bearer and a split bearer as shown inFIG. 6. NR RRC may be located in master gNB and SRBs may be configuredas a MCG bearer type and may use the radio resources of the master gNB.Multi-connectivity may also be described as having at least one bearerconfigured to use radio resources provided by the secondary gNB.Multi-connectivity may or may not be configured/implemented in exampleembodiments of the invention.

In the case of multi-connectivity, the UE may be configured withmultiple NR MAC entities: one NR MAC entity for master gNB, and other NRMAC entities for secondary gNBs. In multi-connectivity, the configuredset of serving cells for a UE may comprise of two subsets: the MasterCell Group (MCG) containing the serving cells of the master gNB, and theSecondary Cell Groups (SCGs) containing the serving cells of thesecondary gNBs. For a SCG, one or more of the following may be applied:at least one cell in the SCG has a configured UL CC and one of them,named PSCell (or PCell of SCG, or sometimes called PCell), is configuredwith PUCCH resources; when the SCG is configured, there may be at leastone SCG bearer or one Split bearer; upon detection of a physical layerproblem or a random access problem on a PSCell, or the maximum number ofNR RLC retransmissions has been reached associated with the SCG, or upondetection of an access problem on a PSCell during a SCG addition or aSCG change: a RRC connection re-establishment procedure may not betriggered, UL transmissions towards cells of the SCG are stopped, amaster gNB may be informed by the UE of a SCG failure type, for splitbearer, the DL data transfer over the master gNB is maintained; the NRRLC AM bearer may be configured for the split bearer; like PCell, PSCellmay not be de-activated; PSCell may be changed with a SCG change (e.g.with security key change and a RACH procedure); and/or a direct bearertype change between a Split bearer and a SCG bearer or simultaneousconfiguration of a SCG and a Split bearer may or may not supported.

With respect to the interaction between a master gNB and secondary gNBsfor multi-connectivity, one or more of the following principles may beapplied: the master gNB may maintain the RRM measurement configurationof the UE and may, (e.g, based on received measurement reports ortraffic conditions or bearer types), decide to ask a secondary gNB toprovide additional resources (serving cells) for a UE; upon receiving arequest from the master gNB, a secondary gNB may create a container thatmay result in the configuration of additional serving cells for the UE(or decide that it has no resource available to do so); for UEcapability coordination, the master gNB may provide (part of) the ASconfiguration and the UE capabilities to the secondary gNB; the mastergNB and the secondary gNB may exchange information about a UEconfiguration by employing of NR RRC containers (inter-node messages)carried in Xn messages; the secondary gNB may initiate a reconfigurationof its existing serving cells (e.g., PUCCH towards the secondary gNB);the secondary gNB may decide which cell is the PSCell within the SCG;the master gNB may or may not change the content of the NR RRCconfiguration provided by the secondary gNB; in the case of a SCGaddition and a SCG SCell addition, the master gNB may provide the latestmeasurement results for the SCG cell(s); both a master gNB and secondarygNBs may know the SFN and subframe offset of each other by OAM, (e.g.,for the purpose of DRX alignment and identification of a measurementgap). In an example, when adding a new SCG SCell, dedicated NR RRCsignaling may be used for sending required system information of thecell as for CA, except for the SFN acquired from a MIB of the PSCell ofa SCG.

In an example, serving cells may be grouped in a TA group (TAG). Servingcells in one TAG may use the same timing reference. For a given TAG,user equipment (UE) may use at least one downlink carrier as a timingreference. For a given TAG, a UE may synchronize uplink subframe andframe transmission timing of uplink carriers belonging to the same TAG.In an example, serving cells having an uplink to which the same TAapplies may correspond to serving cells hosted by the same receiver. AUE supporting multiple TAs may support two or more TA groups. One TAgroup may contain the PCell and may be called a primary TAG (pTAG). In amultiple TAG configuration, at least one TA group may not contain thePCell and may be called a secondary TAG (sTAG). In an example, carrierswithin the same TA group may use the same TA value and/or the sametiming reference. When DC is configured, cells belonging to a cell group(MCG or SCG) may be grouped into multiple TAGs including a pTAG and oneor more sTAGs.

FIG. 8 shows example TAG configurations as per an aspect of anembodiment of the present invention. In Example 1, pTAG comprises PCell,and an sTAG comprises SCell1. In Example 2, a pTAG comprises a PCell andSCell1, and an sTAG comprises SCell2 and SCell3. In Example 3, pTAGcomprises PCell and SCell1, and an sTAG1 includes SCell2 and SCell3, andsTAG2 comprises SCell4. Up to four TAGs may be supported in a cell group(MCG or SCG) and other example TAG configurations may also be provided.In various examples in this disclosure, example mechanisms are describedfor a pTAG and an sTAG. Some of the example mechanisms may be applied toconfigurations with multiple sTAGs.

In an example, an eNB may initiate an RA procedure via a PDCCH order foran activated SCell. This PDCCH order may be sent on a scheduling cell ofthis SCell. When cross carrier scheduling is configured for a cell, thescheduling cell may be different than the cell that is employed forpreamble transmission, and the PDCCH order may include an SCell index.At least a non-contention based RA procedure may be supported forSCell(s) assigned to sTAG(s).

FIG. 9 is an example message flow in a random access process in asecondary TAG as per an aspect of an embodiment of the presentinvention. An eNB transmits an activation command 600 to activate anSCell. A preamble 602 (Msg1) may be sent by a UE in response to a PDCCHorder 601 on an SCell belonging to an sTAG. In an example embodiment,preamble transmission for SCells may be controlled by the network usingPDCCH format 1A. Msg2 message 603 (RAR: random access response) inresponse to the preamble transmission on the SCell may be addressed toRA-RNTI in a PCell common search space (CSS). Uplink packets 604 may betransmitted on the SCell in which the preamble was transmitted.

According to some of the various aspects of embodiments, initial timingalignment may be achieved through a random access procedure. This mayinvolve a UE transmitting a random access preamble and an eNB respondingwith an initial TA command NTA (amount of timing advance) within arandom access response window. The start of the random access preamblemay be aligned with the start of a corresponding uplink subframe at theUE assuming NTA=0. The eNB may estimate the uplink timing from therandom access preamble transmitted by the UE. The TA command may bederived by the eNB based on the estimation of the difference between thedesired UL timing and the actual UL timing. The UE may determine theinitial uplink transmission timing relative to the correspondingdownlink of the sTAG on which the preamble is transmitted.

The mapping of a serving cell to a TAG may be configured by a servingeNB with RRC signaling. The mechanism for TAG configuration andreconfiguration may be based on RRC signaling. According to some of thevarious aspects of embodiments, when an eNB performs an SCell additionconfiguration, the related TAG configuration may be configured for theSCell. In an example embodiment, an eNB may modify the TAG configurationof an SCell by removing (releasing) the SCell and adding(configuring) anew SCell (with the same physical cell ID and frequency) with an updatedTAG ID. The new SCell with the updated TAG ID may initially be inactivesubsequent to being assigned the updated TAG ID. The eNB may activatethe updated new SCell and start scheduling packets on the activatedSCell. In an example implementation, it may not be possible to changethe TAG associated with an SCell, but rather, the SCell may need to beremoved and a new SCell may need to be added with another TAG. Forexample, if there is a need to move an SCell from an sTAG to a pTAG, atleast one RRC message, for example, at least one RRC reconfigurationmessage, may be send to the UE to reconfigure TAG configurations byreleasing the SCell and then configuring the SCell as a part of the pTAG(when an SCell is added/configured without a TAG index, the SCell may beexplicitly assigned to the pTAG). The PCell may not change its TA groupand may be a member of the pTAG.

The purpose of an RRC connection reconfiguration procedure may be tomodify an RRC connection, (e.g. to establish, modify and/or release RBs,to perform handover, to setup, modify, and/or release measurements, toadd, modify, and/or release SCells). If the received RRC ConnectionReconfiguration message includes the sCellToReleaseList, the UE mayperform an SCell release. If the received RRC Connection Reconfigurationmessage includes the sCellToAddModList, the UE may perform SCelladditions or modification.

In LTE Release-10 and Release-11 CA, a PUCCH is only transmitted on thePCell (PSCell) to an eNB. In LTE-Release 12 and earlier, a UE maytransmit PUCCH information on one cell (PCell or PSCell) to a given eNB.

As the number of CA capable UEs and also the number of aggregatedcarriers increase, the number of PUCCHs and also the PUCCH payload sizemay increase. Accommodating the PUCCH transmissions on the PCell maylead to a high PUCCH load on the PCell. A PUCCH on an SCell may beintroduced to offload the PUCCH resource from the PCell. More than onePUCCH may be configured for example, a PUCCH on a PCell and anotherPUCCH on an SCell. In the example embodiments, one, two or more cellsmay be configured with PUCCH resources for transmitting CSI/ACK/NACK toa base station. Cells may be grouped into multiple PUCCH groups, and oneor more cell within a group may be configured with a PUCCH. In anexample configuration, one SCell may belong to one PUCCH group. SCellswith a configured PUCCH transmitted to a base station may be called aPUCCH SCell, and a cell group with a common PUCCH resource transmittedto the same base station may be called a PUCCH group.

In an example embodiment, a MAC entity may have a configurable timertimeAlignmentTimer per TAG. The timeAlignmentTimer may be used tocontrol how long the MAC entity considers the Serving Cells belonging tothe associated TAG to be uplink time aligned. The MAC entity may, when aTiming Advance Command MAC control element is received, apply the TimingAdvance Command for the indicated TAG; start or restart thetimeAlignmentTimer associated with the indicated TAG. The MAC entitymay, when a Timing Advance Command is received in a Random AccessResponse message for a serving cell belonging to a TAG and/orif theRandom Access Preamble was not selected by the MAC entity, apply theTiming Advance Command for this TAG and start or restart thetimeAlignmentTimer associated with this TAG. Otherwise, if thetimeAlignmentTimer associated with this TAG is not running, the TimingAdvance Command for this TAG may be applied and the timeAlignmentTimerassociated with this TAG started. When the contention resolution isconsidered not successful, a timeAlignmentTimer associated with this TAGmay be stopped. Otherwise, the MAC entity may ignore the received TimingAdvance Command.

In example embodiments, a timer is running once it is started, until itis stopped or until it expires; otherwise it may not be running. A timercan be started if it is not running or restarted if it is running. Forexample, a timer may be started or restarted from its initial value.

Example embodiments of the invention may enable operation ofmulti-carrier communications. Other example embodiments may comprise anon-transitory tangible computer readable media comprising instructionsexecutable by one or more processors to cause operation of multi-carriercommunications. Yet other example embodiments may comprise an article ofmanufacture that comprises a non-transitory tangible computer readablemachine-accessible medium having instructions encoded thereon forenabling programmable hardware to cause a device (e.g. wirelesscommunicator, UE, base station, etc.) to enable operation ofmulti-carrier communications. The device may include processors, memory,interfaces, and/or the like. Other example embodiments may comprisecommunication networks comprising devices such as base stations,wireless devices (or user equipment: UE), servers, switches, antennas,and/or the like.

FIG. 11A, FIG. 11B, FIG. 11C, FIG. 11D, FIG. 11E, and FIG. 11F areexample diagrams for architectures of tight interworking between 5G RANand LTE RAN as per an aspect of an embodiment of the present invention.The tight interworking may enable a multiple RX/TX UE in RRC_CONNECTEDto be configured to utilize radio resources provided by two schedulerslocated in two base stations (e.g. (e)LTE eNB and gNB) connected via anon-ideal or ideal backhaul over the Xx interface between LTE eNB andgNB or the Xn interface between eLTE eNB and gNB. Base stations involvedin tight interworking for a certain UE may assume two different roles: abase station may either act as a master base station or as a secondarybase station. In tight interworking, a UE may be connected to one masterbase station and one secondary base station. Mechanisms implemented intight interworking may be extended to cover more than two base stations.

In FIG. 11A and FIG. 11B, a master base station may be an LTE eNB, whichmay be connected to EPC nodes (e.g. to an MME via the S1-C interface andto an S-GW via the S1-U interface), and a secondary base station may bea gNB, which may be a non-standalone node having a control planeconnection via an Xx-C interface to an LTE eNB. In the tightinterworking architecture of FIG. 11A, a user plane for a gNB may beconnected to an S-GW through an LTE eNB via an Xx-U interface betweenLTE eNB and gNB and an S1-U interface between LTE eNB and S-GW. In thearchitecture of FIG. 11B, a user plane for a gNB may be connecteddirectly to an S-GW via an S1-U interface between gNB and S-GW.

In FIG. 11C and FIG. 11D, a master base station may be a gNB, which maybe connected to NGC nodes (e.g. to a control plane core node via theNG-C interface and to a user plane core node via the NG-U interface),and a secondary base station may be an eLTE eNB, which may be anon-standalone node having a control plane connection via an Xn-Cinterface to a gNB. In the tight interworking architecture of FIG. 11C,a user plane for an eLTE eNB may be connected to a user plane core nodethrough a gNB via an Xn-U interface between eLTE eNB and gNB and an NG-Uinterface between gNB and user plane core node. In the architecture ofFIG. 11D, a user plane for an eLTE eNB may be connected directly to auser plane core node via an NG-U interface between eLTE eNB and userplane core node.

In FIG. 11E and FIG. 11F, a master base station may be an eLTE eNB,which may be connected to NGC nodes (e.g. to a control plane core nodevia the NG-C interface and to a user plane core node via the NG-Uinterface), and a secondary base station may be a gNB, which may be anon-standalone node having a control plane connection via an Xn-Cinterface to an eLTE eNB. In the tight interworking architecture of FIG.11E, a user plane for a gNB may be connected to a user plane core nodethrough an eLTE eNB via an Xn-U interface between eLTE eNB and gNB andan NG-U interface between eLTE eNB and user plane core node. In thearchitecture of FIG. 11F, a user plane for a gNB may be connecteddirectly to a user plane core node via an NG-U interface between gNB anduser plane core node.

FIG. 12A, FIG. 12B, and FIG. 12C are example diagrams for radio protocolstructures of tight interworking bearers as per an aspect of anembodiment of the present invention. In FIG. 12A, an LTE eNB may be amaster base station, and a gNB may be a secondary base station. In FIG.12B, a gNB may be a master base station, and an eLTE eNB may be asecondary base station. In FIG. 12C, an eLTE eNB may be a master basestation, and a gNB may be a secondary base station. In 5G network, theradio protocol architecture that a particular bearer uses may depend onhow the bearer is setup. Three alternatives may exist, an MCG bearer, anSCG bearer, and a split bearer as shown in FIG. 12A, FIG. 12B, and FIG.12C. NR RRC may be located in master base station, and SRBs may beconfigured as an MCG bearer type and may use the radio resources of themaster base station. Tight interworking may also be described as havingat least one bearer configured to use radio resources provided by thesecondary base station. Tight interworking may or may not beconfigured/implemented in example embodiments of the invention.

In the case of tight interworking, the UE may be configured with two MACentities: one MAC entity for master base station, and one MAC entity forsecondary base station. In tight interworking, the configured set ofserving cells for a UE may comprise of two subsets: the Master CellGroup (MCG) containing the serving cells of the master base station, andthe Secondary Cell Group (SCG) containing the serving cells of thesecondary base station. For a SCG, one or more of the following may beapplied: at least one cell in the SCG has a configured UL CC and one ofthem, named PSCell (or PCell of SCG, or sometimes called PCell), isconfigured with PUCCH resources; when the SCG is configured, there maybe at least one SCG bearer or one split bearer; upon detection of aphysical layer problem or a random access problem on a PSCell, or themaximum number of (NR) RLC retransmissions has been reached associatedwith the SCG, or upon detection of an access problem on a PSCell duringa SCG addition or a SCG change: a RRC connection re-establishmentprocedure may not be triggered, UL transmissions towards cells of theSCG are stopped, a master base station may be informed by the UE of aSCG failure type, for split bearer, the DL data transfer over the masterbase station is maintained; the RLC AM bearer may be configured for thesplit bearer; like PCell, PSCell may not be de-activated; PSCell may bechanged with a SCG change (e.g. with security key change and a RACHprocedure); and/or neither a direct bearer type change between a Splitbearer and a SCG bearer nor simultaneous configuration of a SCG and aSplit bearer are supported.

With respect to the interaction between a master base station and asecondary base station, one or more of the following principles may beapplied: the master base station may maintain the RRM measurementconfiguration of the UE and may, (e.g, based on received measurementreports, traffic conditions, or bearer types), decide to ask a secondarybase station to provide additional resources (serving cells) for a UE;upon receiving a request from the master base station, a secondary basestation may create a container that may result in the configuration ofadditional serving cells for the UE (or decide that it has no resourceavailable to do so); for UE capability coordination, the master basestation may provide (part of) the AS configuration and the UEcapabilities to the secondary base station; the master base station andthe secondary base station may exchange information about a UEconfiguration by employing of RRC containers (inter-node messages)carried in Xn or Xx messages; the secondary base station may initiate areconfiguration of its existing serving cells (e.g., PUCCH towards thesecondary base station); the secondary base station may decide whichcell is the PSCell within the SCG; the master base station may notchange the content of the RRC configuration provided by the secondarybase station; in the case of a SCG addition and a SCG SCell addition,the master base station may provide the latest measurement results forthe SCG cell(s); both a master base station and a secondary base stationmay know the SFN and subframe offset of each other by OAM, (e.g., forthe purpose of DRX alignment and identification of a measurement gap).In an example, when adding a new SCG SCell, dedicated RRC signaling maybe used for sending required system information of the cell as for CA,except for the SFN acquired from a MIB of the PSCell of a SCG.

FIG. 13A and FIG. 13B are example diagrams for gNB deployment scenariosas per an aspect of an embodiment of the present invention. In thenon-centralized deployment scenario in FIG. 13A, the full protocol stack(e.g. NR RRC, NR PDCP, NR RLC, NR MAC, and NR PHY) may be supported atone node. In the centralized deployment scenario in FIG. 13B, upperlayers of gNB may be located in a Central Unit (CU), and lower layers ofgNB may be located in Distributed Units (DU). The CU-DU interface (e.g.Fs interface) connecting CU and DU may be ideal or non-ideal. Fs-C mayprovide a control plane connection over Fs interface, and Fs-U mayprovide a user plane connection over Fs interface. In the centralizeddeployment, different functional split options between CU and DUs may bepossible by locating different protocol layers (RAN functions) in CU andDU. The functional split may support flexibility to move RAN functionsbetween CU and DU depending on service requirements and/or networkenvironments. The functional split option may change during operationafter Fs interface setup procedure, or may change only in Fs setupprocedure (i.e. static during operation after Fs setup procedure).

FIG. 14 is an example diagram for different functional split optionexamples of the centralized gNB deployment scenario as per an aspect ofan embodiment of the present invention. In the split option example 1,an NR RRC may be in CU, and NR PDCP, NR RLC, NR MAC, NR PHY, and RF maybe in DU. In the split option example 2, an NR RRC and NR PDCP may be inCU, and NR RLC, NR MAC, NR PHY, and RF may be in DU. In the split optionexample 3, an NR RRC, NR PDCP, and partial function of NR RLC may be inCU, and the other partial function of NR RLC, NR MAC, NR PHY, and RF maybe in DU. In the split option example 4, an NR RRC, NR PDCP, and NR RLCmay be in CU, and NR MAC, NR PHY, and RF may be in DU. In the splitoption example 5, an NR RRC, NR PDCP, NR RLC, and partial function of NRMAC may be in CU, and the other partial function of NR MAC, NR PHY, andRF may be in DU. In the split option example 6, an NR RRC, NR PDCP, NRRLC, and NR MAC may be in CU, and NR PHY and RF may be in DU. In thesplit option example 7, an NR RRC, NR PDCP, NR RLC, NR MAC, and partialfunction of NR PHY may be in CU, and the other partial function of NRPHY and RF may be in DU. In the split option example 8, an NR RRC, NRPDCP, NR RLC, NR MAC, and NR PHY may be in CU, and RF may be in DU.

The functional split may be configured per CU, per DU, per UE, perbearer, per slice, or with other granularities. In per CU split, a CUmay have a fixed split, and DUs may be configured to match the splitoption of CU. In per DU split, each DU may be configured with adifferent split, and a CU may provide different split options fordifferent DUs. In per UE split, a gNB (CU and DU) may provide differentsplit options for different UEs. In per bearer split, different splitoptions may be utilized for different bearer types. In per slice splice,different split options may be applied for different slices.

In an example embodiment, the new radio access network (new RAN) maysupport different network slices, which may allow differentiatedtreatment customized to support different service requirements with endto end scope. The new RAN may provide a differentiated handling oftraffic for different network slices that may be pre-configured, and mayallow a single RAN node to support multiple slices. The new RAN maysupport selection of a RAN part for a given network slice, by one ormore slice ID(s) or NSSAI(s) provided by a UE or a NGC (e.g. NG CP). Theslice ID(s) or NSSAI(s) may identify one or more of pre-configurednetwork slices in a PLMN. For initial attach, a UE may provide a sliceID and/or an NSSAI, and a RAN node (e.g. gNB) may use the slice ID orthe NSSAI for routing an initial NAS signaling to an NGC control planefunction (e.g. NG CP). If a UE does not provide any slice ID or NSSAI, aRAN node may send a NAS signaling to a default NGC control planefunction. For subsequent accesses, the UE may provide a temporary ID fora slice identification, which may be assigned by the NGC control planefunction, to enable a RAN node to route the NAS message to a relevantNGC control plane function. The new RAN may support resource isolationbetween slices. The RAN resource isolation may be achieved by avoidingthat shortage of shared resources in one slice breaks a service levelagreement for another slice.

The amount of data traffic carried over cellular networks is expected toincrease for many years to come. The number of users/devices isincreasing and each user/device accesses an increasing number andvariety of services, e.g. video delivery, large files, images. Thisrequires not only high capacity in the network, but also provisioningvery high data rates to meet customers' expectations on interactivityand responsiveness. More spectrum is therefore needed for cellularoperators to meet the increasing demand. Considering user expectationsof high data rates along with seamless mobility, it is beneficial thatmore spectrum be made available for deploying macro cells as well assmall cells for cellular systems.

Striving to meet the market demands, there has been increasing interestfrom operators in deploying some complementary access utilizingunlicensed spectrum to meet the traffic growth. This is exemplified bythe large number of operator-deployed Wi-Fi networks and the 3GPPstandardization of LTE/WLAN interworking solutions. This interestindicates that unlicensed spectrum, when present, can be an effectivecomplement to licensed spectrum for cellular operators to helpaddressing the traffic explosion in some scenarios, such as hotspotareas. LAA offers an alternative for operators to make use of unlicensedspectrum while managing one radio network, thus offering newpossibilities for optimizing the network's efficiency.

In an example embodiment, Listen-before-talk (clear channel assessment)may be implemented for transmission in an LAA cell. In alisten-before-talk (LBT) procedure, equipment may apply a clear channelassessment (CCA) check before using the channel. For example, the CCAutilizes at least energy detection to determine the presence or absenceof other signals on a channel in order to determine if a channel isoccupied or clear, respectively. For example, European and Japaneseregulations mandate the usage of LBT in the unlicensed bands. Apart fromregulatory requirements, carrier sensing via LBT may be one way for fairsharing of the unlicensed spectrum.

In an example embodiment, discontinuous transmission on an unlicensedcarrier with limited maximum transmission duration may be enabled. Someof these functions may be supported by one or more signals to betransmitted from the beginning of a discontinuous LAA downlinktransmission. Channel reservation may be enabled by the transmission ofsignals, by an LAA node, after gaining channel access via a successfulLBT operation, so that other nodes that receive the transmitted signalwith energy above a certain threshold sense the channel to be occupied.Functions that may need to be supported by one or more signals for LAAoperation with discontinuous downlink transmission may include one ormore of the following: detection of the LAA downlink transmission(including cell identification) by UEs; time & frequency synchronizationof UEs.

In an example embodiment, DL LAA design may employ subframe boundaryalignment according to LTE-A carrier aggregation timing relationshipsacross serving cells aggregated by CA. This may not imply that the eNBtransmissions can start only at the subframe boundary. LAA may supporttransmitting PDSCH when not all OFDM symbols are available fortransmission in a subframe according to LBT. Delivery of necessarycontrol information for the PDSCH may also be supported.

LBT procedure may be employed for fair and friendly coexistence of LAAwith other operators and technologies operating in unlicensed spectrum.LBT procedures on a node attempting to transmit on a carrier inunlicensed spectrum require the node to perform a clear channelassessment to determine if the channel is free for use. An LBT proceduremay involve at least energy detection to determine if the channel isbeing used. For example, regulatory requirements in some regions, e.g.,in Europe, specify an energy detection threshold such that if a nodereceives energy greater than this threshold, the node assumes that thechannel is not free. While nodes may follow such regulatoryrequirements, a node may optionally use a lower threshold for energydetection than that specified by regulatory requirements. In an example,LAA may employ a mechanism to adaptively change the energy detectionthreshold, e.g., LAA may employ a mechanism to adaptively lower theenergy detection threshold from an upper bound. Adaptation mechanism maynot preclude static or semi-static setting of the threshold. In anexample Category 4 LBT mechanism or other type of LBT mechanisms may beimplemented.

Various example LBT mechanisms may be implemented. In an example, forsome signals, in some implementation scenarios, in some situations,and/or in some frequencies no LBT procedure may performed by thetransmitting entity. In an example, Category 2 (e.g. LBT without randomback-off) may be implemented. The duration of time that the channel issensed to be idle before the transmitting entity transmits may bedeterministic. In an example, Category 3 (e.g. LBT with random back-offwith a contention window of fixed size) may be implemented. The LBTprocedure may have the following procedure as one of its components. Thetransmitting entity may draw a random number N within a contentionwindow. The size of the contention window may be specified by theminimum and maximum value of N. The size of the contention window may befixed. The random number N may be employed in the LBT procedure todetermine the duration of time that the channel is sensed to be idlebefore the transmitting entity transmits on the channel. In an example,Category 4 (e.g. LBT with random back-off with a contention window ofvariable size) may be implemented. The transmitting entity may draw arandom number N within a contention window. The size of contentionwindow may be specified by the minimum and maximum value of N. Thetransmitting entity may vary the size of the contention window whendrawing the random number N. The random number N is used in the LBTprocedure to determine the duration of time that the channel is sensedto be idle before the transmitting entity transmits on the channel.

LAA may employ uplink LBT at the UE. The UL LBT scheme may be differentfrom the DL LBT scheme (e.g. by using different LBT mechanisms orparameters) for example, since the LAA UL is based on scheduled accesswhich affects a UE's channel contention opportunities. Otherconsiderations motivating a different UL LBT scheme include, but are notlimited to, multiplexing of multiple UEs in a single subframe.

In an example, a DL transmission burst may be a continuous transmissionfrom a DL transmitting node with no transmission immediately before orafter from the same node on the same CC. An UL transmission burst from aUE perspective may be a continuous transmission from a UE with notransmission immediately before or after from the same UE on the sameCC. In an example, UL transmission burst is defined from a UEperspective. In an example, an UL transmission burst may be defined froman eNB perspective. In an example, in case of an eNB operating DL+UL LAAover the same unlicensed carrier, DL transmission burst(s) and ULtransmission burst(s) on LAA may be scheduled in a TDM manner over thesame unlicensed carrier. For example, an instant in time may be part ofa DL transmission burst or an UL transmission burst.

Distributed Unit Connection Issue

In an example, a base station may consider radio resource condition andtraffic status to configure wireless device control parameters, resourceconfiguration parameters, and/or cell configuration parameters. In thefunctional split scenario, a base station central unit configureswireless device control parameters, and a base station distributed unitmay monitor radio resource condition and traffic status of thedistributed unit. In an existing technology, a base station CU may haveless information of lower layer radio condition (e.g. physical layer,MAC layer, RLC layer, and/or the like). When a central unit configurewireless device configuration parameters, resource parameters, and/orcell configuration parameters, the lack of lower layer radio conditionand/or status information may cause inappropriate configurations, whichmay decrease cellular system performance. The inappropriateconfiguration may cause increased call dropping ratio, packet errorrate, and/or packet transmission delay, and further may decreasecommunication reliability and/or increase data transmission latency.

Example implementation of embodiments may support a base station centralunit to consider lower layer radio condition information and/or trafficstatus of cells. In an example embodiment, a distributed unit (DU) maytransmit a radio link state information for a wireless device to acentral unit (CU). The radio link state information may comprise one ormore indications indicating that the wireless device may experience aradio link failure and/or that the distributed radio access networkentity may lose a connection with the wireless device. The central unitmay determine a radio link failure of the wireless device at least basedon one or more elements of the radio link state information, and/or maydetermine to release a wireless device context of the wireless device.Example implementation of embodiments may increase communicationreliability and/or reduce data transmission latency of wirelesscommunication systems.

In an example, a cell may be operated with one or more beams employing amulti-antenna system, as shown in FIG. 27. A beam may have a spatialdirection, and/or may cover a part of a cell coverage area. Acombination of one or more beam spatial areas may form a cell coverage.In an example, a beam transmitting a synchronization signal and/orreceiving a signal from a wireless device may be swept over a cellcoverage area in a predetermined way. A synchronization signal index, asynchronization signal scheduling information, and/or a synchronizationsignal sequence information may be used to identify a swept beam. Aswept beam may broadcast one or more control information comprising atleast one of a system information, a master information, a PDCCH, aPRACH resource, a random access preamble information, a synchronizationsignal, a reference signal, and/or the like. In an example, a beam maytransmit a reference signal (e.g. CSI-RS). A beam may be also identifiedby a reference signal (e.g. CSI-RS, DM-RS, and the like) index, areference signal scheduling information, and/or a reference signalsequence information.

In an example, one or more beams may be managed via a set of L1/L2procedures to acquire and maintain a set of TRP(s)(TransmissionReception Point) and/or UE beams that may be used for DL and ULtransmission/reception, which may include at least following aspects:Beam determination (for TRP(s) or UE to select of its own Tx/Rxbeam(s)), Beam measurement (for TRP(s) or UE to measure characteristicsof received beamformed signals), Beam reporting (for UE to reportinformation of beamformed signal(s) based on beam measurement), and/orBeam sweeping (operation of covering a spatial area, with beamstransmitted and/or received during a time interval in a predeterminedway).

In an example, the followings may be defined as Tx/Rx beamcorrespondence at TRP and UE. Tx/Rx beam correspondence at TRP holds ifat least one of the following is satisfied: TRP may be able to determinea TRP Rx beam for the uplink reception based on UE's downlinkmeasurement on TRP's one or more Tx beams; and/or TRP may be able todetermine a TRP Tx beam for the downlink transmission based on TRP'suplink measurement on TRP's one or more Rx beams. Tx/Rx beamcorrespondence at UE may hold if at least one of the following issatisfied: UE may be able to determine a UE Tx beam for the uplinktransmission based on UE's downlink measurement on UE's one or more Rxbeams; UE may be able to determine a UE Rx beam for the downlinkreception based on TRP's indication based on uplink measurement on UE'sone or more Tx beams; and/or capability indication of UE beamcorrespondence related information to TRP may be supported.

In an example, the following DL L1/L2 beam management procedures (e.g.P-1, P-2, and P-3) may be supported within one or multiple TRPs. P-1 maybe used to enable UE measurement on different TRP Tx beams to supportselection of TRP Tx beams/UE Rx beam(s). For beamforming at TRP, ittypically may include a intra/inter-TRP Tx beam sweep from a set ofdifferent beams. For beamforming at UE, it may include a UE Rx beamsweep from a set of different beams. P-2 may be used to enable UEmeasurement on different TRP Tx beams to possibly change inter/intra-TRPTx beam(s). From a possibly smaller set of beams for beam refinementthan in P-1. P-2 may be a special case of P-1. P-3 may be used to enableUE measurement on the same TRP Tx beam to change UE Rx beam in the caseUE uses beamforming. At least network triggered aperiodic beam reportingmay be supported under P-1, P-2, and P-3 related operations.

In an example, UE measurement based on RS for beam management (at leastCSI-RS) may be composed of K (=total number of configured beams) beams,and/or UE may report measurement results of N selected Tx beams, where Nmay not be necessarily fixed number. The procedure based on RS formobility purpose may be not precluded. Reporting information may atleast include measurement quantities for N beam (s) and informationindicating N DL Tx beam(s), if N<K. Specifically, when a UE isconfigured with K′>1 non-zero power (NZP) CSI-RS resources, a UE mayreport N′ CRIs (CSI-RS Resource Indicator). A UE may be configured withthe following high layer parameters for beam management. N≥1 reportingsettings, M≥1 resource settings: the links between reporting settingsand resource settings may be configured in the agreed CSI measurementsetting; CSI-RS based P-1 & P-2 may be supported with resource andreporting settings; and/or P-3 may be supported with or withoutreporting setting. A reporting setting at least including: informationindicating selected beam(s); L1 measurement reporting; time-domainbehavior, e.g. aperiodic, periodic, semi-persistent; and/orfrequency-granularity if multiple frequency granularities are supported.A resource setting at least including: time-domain behavior, e.g.aperiodic, periodic, semi-persistent; RS type, e.g. NZP CSI-RS at least;at least one CSI-RS resource set, with each CSI-RS resource set havingK≥1 CSI-RS resources (Some parameters of K CSI-RS resources may be thesame, e.g. port number, time-domain behavior, density and periodicity ifany).

In an example, a beam reporting may be supported at least based on analternative 1 as follow. UE may report information about TRP Tx Beam(s)that may be received using selected UE Rx beam set(s) where a Rx beamset may refer to a set of UE Rx beams that may be used for receiving aDL signal. It may be UE implementation issues on how to construct the Rxbeam set. One example may be that each of Rx beam in a UE Rx beam setmay correspond to a selected Rx beam in each panel. For UEs with morethan one UE Rx beam sets, the UE may report TRP Tx Beam(s) and anidentifier of the associated UE Rx beam set per reported TX beam(s).Different TRP Tx beams reported for the same Rx beam set may be receivedsimultaneously at the UE. Different TRP TX beams reported for differentUE Rx beam set may not be possible to be received simultaneously at theUE.

In an example, a beam reporting may be supported at least based on analternative 2 as follow. UE may report information about TRP Tx Beam(s)per UE antenna group basis where UE antenna group may refer to receiveUE antenna panel or subarray. For UEs with more than one UE antennagroup, the UE may report TRP Tx Beam(s) and an identifier of theassociated UE antenna group per reported TX beam. Different TX beamsreported for different antenna groups may be received simultaneously atthe UE. Different TX beams reported for the same UE antenna group maynot be possible to be received simultaneously at the UE.

In an example, NR may support the following beam reporting considering Lgroups where L>=1 and/or each group may refer to a Rx beam set(alternative 1) or a UE antenna group (alternative 2) depending on whichalternative may be adopted. For each group L, UE may report at least thefollowing information: information indicating group at least for somecases; measurement quantities for N_L beam(s), which may support L1 RSRPand CSI report (when CSI-RS is for CSI acquisition); and/or informationindicating N_L DL Tx beam(s) when applicable. This group based beamreporting may be configurable per UE basis. This group based beamreporting may be turned off per UE basis, e.g. when L=1 or N_L=1. Groupidentifier may not be reported when it is turned off.

In an example, NR (New Radio) may support that UE may be able to triggermechanism to recover from beam failure. Beam failure event may occurwhen the quality of beam pair link(s) of an associated control channelfalls low enough (e.g. comparison with a threshold, time-out of anassociated timer). Mechanism to recover from beam failure may betriggered when beam failure occurs. The beam pair link may be used forconvenience, and may or may not be used in specification. Network mayconfigure to UE with resources for UL transmission of signals forrecovery purpose. Configurations of resources may be supported where thebase station may be listening from all or partial directions, e.g.random access region. The UL transmission/resources to report beamfailure may be located in the same time instance as PRACH (resourcesorthogonal to PRACH resources) and/or at a time instance (configurablefor a UE) different from PRACH. Transmission of DL signal may besupported for allowing the UE to monitor the beams for identifying newpotential beams.

In an example, NR may support beam management with and withoutbeam-related indication. When beam-related indication is provided,information pertaining to UE-side beamforming/receiving procedure usedfor CSI-RS-based measurement may be indicated through QCL (QuasiCo-Location) to UE. NR may support using the same or different beams oncontrol channel and the corresponding data channel transmissions.

In an example, for NR-PDCCH transmission supporting robustness againstbeam pair link blocking, UE may be configured to monitor NR-PDCCH on Mbeam pair links simultaneously, where M≥1 and the maximum value of M maydepend at least on UE capability. UE may be configured to monitorNR-PDCCH on different beam pair link(s) in different NR-PDCCH OFDMsymbols. Parameters related to UE Rx beam setting for monitoringNR-PDCCH on multiple beam pair links may be configured by higher layersignaling or MAC CE and/or considered in the search space design. Atleast, NR may support indication of spatial QCL assumption between an DLRS antenna port(s), and DL RS antenna port(s) for demodulation of DLcontrol channel. Candidate signaling methods for beam indication for aNR-PDCCH (i.e. configuration method to monitor NR-PDCCH) may be MAC CEsignaling, RRC signaling, DCI signaling, specification-transparentand/or implicit method, and combination of these signaling methods.Indication may not be needed for some cases.

In an example, for reception of unicast DL data channel, NR may supportindication of spatial QCL assumption between DL RS antenna port(s) andDMRS antenna port(s) of DL data channel. Information indicating the RSantenna port(s) may be indicated via DCI (downlink grants). Theinformation may indicate the RS antenna port(s) which may be QCL-ed withDMRS antenna port(s). Different set of DMRS antenna port(s) for the DLdata channel may be indicated as QCL with different set of RS antennaport(s). Indication may not be needed for some cases.

In an example, a CU-DU interface between CU and DU may be defined as anF1 interface. In an example, there may be transport networks withperformances that may vary from high transport latency to low transportlatency in the real deployment. For transport network with highertransport latency, higher layer splits may be applicable. For transportnetwork with lower transport latency, lower layer splits may also beapplicable and preferable to realize enhanced performance (e.g.centralized scheduling). Thus, preferable option may be differentbetween different types of transport networks (ranging from lower layersplit for transport networks with lower transport latency to higherlayer split for transport networks with higher transport latency).Furthermore, within lower layer split discussion, there may be bothdemands to reduce transport bandwidth and demands to support efficientscheduling and advanced receivers.

In an example, LTE<->NR interworking may be based onDual-Connectivity-like mechanisms. Such approach may not imply aparticular functional split. The requirement that may be extrapolated bythe LTE-NR tight interworking requirement may be that of allowingaggregation of PDCP functionalities, in case of split bearers.

In an example, some possible options for the granularity of the CU/DUfunctional split may be per CU (each CU may a fixed split, and DUs maybe configured to match this) and/or per DU (each DU may be configuredwith a different split. The choice of a DU split may depend on specifictopology or backhaul support in an area). For 2 cases, one possible wayon how the CU/DU decide or coordinate the split may be throughconfiguration. Alternatively, the split may be negotiated taking intoaccount capabilities of the two units (CU and DU), and deploymentpreference e.g. based on backhaul topology. In an example, additionalsplit granularity options may be as followings: per UE (different UEsmay have different service levels, or belong to different categories,that may be best served in different ways by the RAN e.g. a low rateIoT-type UE with no need for low latency may not necessarily requirehigher layer functions close to the RF), per bearer (different bearersmay have different QOS requirements that may be best supported bydifferent functionality mapping. For example, QCI=1 type bearer mayrequire low delay but may not not SDU error sensitive, while eMBB maynot be delay sensitive but may have challenging requirements onthroughput and SDU error rate), and/or per slice (it may be expectedthat each slice may have at least some distinctive QOS requirements.Regardless of how exactly a slice is implemented within the RAN,different functionality mapping may be suitable for each slice).

Per CU and Per DU options may pertain to flexibility of networktopology, and may be straightforward to support. Whether procedures maybe required to handle the initial configuration (or O&M may be reliedupon) may not be discussed during the study phase. Note that in the PerDU option, one CU may need to support different split levels indifferent interfaces, which may not the case in the Per CU option.Further granularity (Per UE, Per bearer, Per slice) may require analysisand justification based on QoS and latency requirements. Note that thePer UE, Per bearer and Per slice options may imply that a particularinstance of the interface between CU/DU may need to supportsimultaneously multiple granularity levels on user plane. The baselinemay be CU based or DU based. If there are demands to have finergranularity (e.g. Per UE, Per bearer, Per slice), justification may bemade clear first.

In an example, dynamicity may imply that the protocol distribution andthe interface between the CU and DU may need to be reconfigured. If theswitching occurs in CU-DU setup procedure (F1 interface setupprocedure), the interface design may not be influenced largely as thesplit option may not be changed during operation. If the switchingoccurs during operation, there may be impact on complexity of interface.

In an example, it may be possible that not all of the defined functionalsplits allow for having RRM functions like Call Admission Control andLoad balancing in the CU controlling multiple DUs. This may allow forthe potential of increased efficiency in inter-cell coordination for RRMfunctions like the coordination of interference management, loadbalancing and Call Admission Control. However, that efficiency may onlybe realized if the CU may have reliable and accurate understanding ofthe current environment at the DU which may include issues beyond justradio conditions, but may include current processing capabilities, or inthe case of wireless or mesh backhauling help in determining currentterrestrial capacity.

In an example, functional split Option 5, Option 6, Option 7 and Option8 may allow for scheduling of data transmission in the CU. Havingcentralized scheduling may provide benefit particularly for interferencemanagement and coordinated transmission in multiple cells (like softhandover in UMTS, or CoMP in LTE). However, this may require the CU tohave an even better understanding of the state of the DU radioconditions than for CAC and other centralized RRM functions. It also mayrequire either very low latency/jitter transport or sufficiently tightcoordination of timing and reception of user plane data (one solutionmay be the window mechanism used on the UP in UMTS), but this may bechallenging particularly for lower latency use cases in NR.Centralization of RAN functions may have strong potential for somebenefits such as reduced cost, improved scalability, more efficientinter-cell coordination for interference management as well as improvedmobility in ultra-dense deployments.

In an example, the RRC related functions may be located in the CU. TheRRC message between the gNB and the UE may be transferred through theinterface (e.g. F1 interface) between the CU and the DU. RRC messagesmay require a differentiated transport between CU and DU compared todata transport, e.g. in terms of robustness and delay.

In an example, F1-C and F1-U may provide C-plane and U-plane over F1interface, respectively. In this architecture, CU and DU may be definedas follows. Central Unit (CU) may be a logical node that may include asubset of the gNB functions as listed excepting those functionsallocated exclusively to the DU. CU may control the operation of DUs.Distributed Unit (DU) may be a logical node that may include, dependingon the functional split option, a subset of the gNB functions. Theoperation of DU may be controlled by the CU.

In an example, gNB-CU UE F1AP ID may be allocated so as to uniquelyidentify the UE over the F1 interface within a gNB-CU and an associatedgNB-DU. When a gNB-DU receives a gNB-CU UE F1AP ID, it may store it forthe duration of the UE-associated logical F1-connection for this UE. ThegNB-CU UE F1AP ID may be unique within the gNB-CU logical node and theassociated gNB-DU logical node. The definition of the AP ID may bepending the decision on whether the DU can be connected to multiple CU.UE-associated signaling may be one or more F1AP messages associated toone UE, wherein the one or more F1AP messages may use the UE-associatedlogical F1-connection for association of the message to the UE in gNB-DUand gNB-CU. The UE-associated logical F1-connection may use theidentities gNB-CU UE F1AP ID. For a received UE associated FLAP message,the gNB-CU and gNB-DU may identify the associated UE based on the gNB-CUUE F1AP ID IE. The UE-associated logical F1-connection may exist beforethe F1 UE context is setup in gNB-DU.

In an example, the purpose of the F1 Setup procedure may be to exchangeapplication level data needed for the gNB-DU and the gNB-CU to correctlyinteroperate on the F1 interface (i.e. CU-DU interface). This proceduremay be the first FLAP procedure triggered after the TNL association mayhave become operational. The procedure may use non-UE associatedsignaling. This procedure may erase existing application levelconfiguration data in the two nodes and may replace it by the onereceived and may clear gNB-CU overload state information at the gNB-DU.If the gNB-DU and gNB-CU do not agree on retaining the UE Contexts, thisprocedure may re-initialize the F1AP UE-related contexts and may eraserelated signaling connections in the two nodes like a Reset procedurewould do.

In an example embodiment, a distributed radio access network entity (DU,distributed unit) may transmit a radio link state information for awireless device to a central radio access network entity (CU, centralunit). The radio link state information may comprise one or moreindications indicating that the wireless device may experience a radiolink failure and/or that the distributed radio access network entity maylose a connection with the wireless device. The central radio accessnetwork entity may determine a radio link failure of the wireless deviceat least based on one or more elements of the radio link stateinformation, and/or may determine to release a wireless device contextof the wireless device.

A NR (New Radio) may support both single beam and multi-beam operations.In a multi-beam system, gNB may need a downlink beam sweep to providecoverage for DL synchronization signals (SSs) and common controlchannels. To enable UEs to access the cell, the UEs may need the similarsweep for UL direction as well.

In the single beam scenarios, the network may configure time-repetitionwithin one synchronization signal (SS) block, which may comprise atleast PSS (Primary synchronization signal), SSS (Secondarysynchronization signal), and PBCH (Physical broadcast channel), in awide beam. In multi-beam scenarios, the network may configure at leastsome of these signals and physical channels (e.g. SS Block) in multiplebeams such that a UE identifies at least OFDM symbol index, slot indexin a radio frame and radio frame number from an SS block.

An RRC_INACTIVE or RRC_IDLE UE may need to assume that an SS Block mayform an SS Block Set and, an SS Block Set Burst, having a givenperiodicity. In multi-beam scenarios, the SS Block may be transmitted inmultiple beams, together forming an SS Burst. If multiple SS Bursts areneeded to transmit beams, these SS Bursts together may form an SS BurstSet as illustrated in FIG. 27. FIG. 27 illustrates examples of differentconfigurations of an SS Burst Set. Top: Time-repetition within one SSBurst in a wide beam. Middle: Beam-sweeping of a small number of beamsusing one SS Burst in the SS Burst Set. Bottom: Beam-sweeping of alarger number of beams using more than one SS Burst in the SS Burst Setto form a complete sweep.

In the multi-beam scenario, for the same cell, PSS/SSS/PBCH may berepeated to support cell selection/reselection and initial accessprocedures. There may be some differences in the conveyed PRACHconfiguration implied by the TSS (Tertiary synchronization signal) on abeam basis within an SS Burst. Under the assumption that PBCH carriesthe PRACH configuration, a gNB may broadcast PRACH configurationspossibly per beam where the TSS may be utilized to imply the PRACHconfiguration differences. FIG. 28 illustrates an example of an RAprocedure comprising broadcasting multiple SS blocks.

In an example, the base station may transmit to a wireless device one ormore messages comprising configuration parameters of one or more cells.The configuration parameters may comprise parameters of a plurality ofCSI-RS signal format and/or resources. Configuration parameters of aCSI-RS may comprise one or more parameters indicating CSI-RSperiodicity, one or more parameters indicating CSI-RS subcarriers (e.g.resource elements), one or more parameters indicating CSI-RS sequence,and/or other parameters. Some of the parameters may be combined into oneor more parameters. A plurality of CSI-RS signals may be configured. Inan example, the one or more message may indicate the correspondencebetween SS blocks and CSI-RS signals. The one or more messages may beRRC connection setup message, RRC connection resume message, and/or RRCconnection reconfiguration message. In an example, a UE in RRC-Idle modemay not be configured with CSI-RS signals and may receive SS blocks andmay measure a pathloss based on SS signals. A UE in RRC-connected mode,may be configured with CSI-RS signals and may be measure pathloss basedon CSI-RS signals. In an example, a UE in RRC inactive mode may measurethe pathloss based on SS blocks, e.g. when the UE moves to a differentbase station that has a different CSI-RS configuration compared with theanchor base station.

Example PRACH burst/RACH resource partitioning: In a multi-beam system,a NR may configure different types of PRACH resources that may beassociated with SS blocks and/or DL beams. In NR, a PRACH transmissionoccasion may be defined as the time-frequency resource on which a UEtransmits a preamble using the configured PRACH preamble format with asingle particular Tx beam and for which gNB performs PRACH preambledetection. One PRACH occasion may be used to cover the beamnon-correspondence case. gNB may perform RX sweep during PRACH occasionas UE TX beam alignment is fixed during single occasion. A PRACH burstmay mean a set of PRACH occasions allocated consecutively in timedomain, and a PRACH burst set may mean a set of PRACH bursts to enablefull RX sweep. FIG. 29 illustrates an example of configured PRACHoccasion, PRACH burst, and PRACH burst set. FIG. 29 illustrates anexample of a RACH Occasion, RACH Burst and RACH Burst Set.

There may be an association between SS blocks (DL signal/channel) andPRACH occasion and a subset of PRACH preamble resources. One PRACHoccasion may comprise a set of preambles. In multi beam operation, thegNB may need to know which beam or set of beams it may use to send RARand the preambles may be used to indicate that. NR may configurefollowing partitioning and mappings in multi beam operation:

The timing from SS block to the PRACH resource may be indicated in theMIB. In an example, different TSS may be used for different timings suchthat the detected sequence within TSS indicates the PRACH resource. ThisPRACH configuration may be specified as a timing relative to the SSblock, and may be given as a combination of the payload in the MIB andanother broadcasted system information.

Association between SS block and a subset of RACH resources and/or asubset of preamble indices may be configured so that TRP may identifythe best DL beam for a UE according to resource location or preambleindex of received preamble. An association may be independent and atleast either a subset of RACH resources or subset of preamble indicesmay not be allowed to be associated with multiple SS blocks.

Example SS-block specific PRACH preamble resources: PRACH resources maybe partitioned on SS-blocks basis in multiple beams operation. There maybe one to one and/or many to one mapping between SS-blocks and PRACHoccasions. FIG. 30 illustrates an example of TDD (FIG. 30(a))/FDD (FIG.30(b)) based one to one mapping and multi-to-one mapping (FIG. 30(c))between SS-blocks and PRACH occasions.

UE may detect SS-block based on DL synchronization signals anddifferentiate SS-blocks based on the time index. With one-to-one mappingof beam or beams used to transmit SS-block and a specific PRACHoccasion, the transmission of PRACH preamble resource may be anindication informed by a UE to gNB of the preferred SS-block. This waythe PRACH preamble resources of single PRACH occasion may correspond tospecific SS-block and mapping may be done based on the SS-block index.There may be one to one mapping between an SS-block beam and a PRACHoccasion. There may not be such mapping for the SS-block periodicity andRACH occasion periodicity.

Depending on the gNB capability (e.g. the used beamformingarchitecture), there may not be one to one mapping between singleSS-block and single RACH occasion. In case beam or beams used fortransmitting SS-block and receiving during RACH occasion do notcorrespond directly, e.g., gNB may form receive beams that covermultiple SS-blocks beams, the preambles of PRACH occasion may be dividedbetween the different SS-blocks in a manner that a subset of PRACHpreambles map to specific SS-block.

FIG. 30 illustrates an example of TDM and FDM mapping of PRACHresources.

Example beam-specific PRACH resources: With beam-specific PRACHresources, a gNB DL TX beam may be associated with a subset ofpreambles. The beam specific PRACH preambles resources may be associatedwith DL TX beams that are identified by periodical beam and cellspecific CSI-RS for L3 Mobility (same signals may be used for L2 beammanagement/intra-cell mobility as well). A UE may detect the beamswithout RRC configuration, e.g., reading the beam configuration fromminimum SI (MIB/SIB).

The PRACH resource mapping to specific beams may use SS-blockassociation. Specific beams may be associated with the beams used fortransmitting SS-block as illustrated in FIG. 31. In left of FIG. 31, gNBmay transmit SS-block using one or multiple beams (in case ofanalogue/hybrid beamforming), but individual beams may not be detected.From the UE perspective, this is a single beam transmission. In right ofFIG. 31, gNB may transmit CSI-RS (for Mobility) using individual beamsassociated with specific SS-block. A UE may detect individual beamsbased on the CSI-RS. The left of FIG. 31 illustrates an example of oneor more beams configured with an SS block and the right of FIG. 31illustrates an example of one or more beams configured with CSI-RS.

PRACH occasion may be mapped to corresponding SS-block, and a set ofPRACH preambles may be divided between beams as illustrated in top ofFIG. 32. Similar to mapping of multiple SS-blocks to single PRACHoccasion, multiple beams of an SS-block may be mapped to at least onePRACH occasion as illustrated in bottom of FIG. 32. The top of FIG. 32illustrates an example of mapping beam specific preambles to PRACHoccasion with one-to-one mapping and the bottom of FIG. 32 illustratesan example of mapping beam specific preambles to PRACH occasion withk-to-one mapping.

If a PRACH occasion is configured with k preambles, and a PRACH occasionis configured to be SS-block specific, the whole set of preambles may beused to indicate the specific SS-block. In this case, there may be NPRACH occasions corresponding to N SS-blocks.

If multiple SS-blocks are mapped to single PRACH occasion, then thepreambles may be divided between SS-blocks and depending on the numberof SS-blocks, the available preambles per SS-block may be K/N (Kpreambles, N SS-blocks).

If K SS-block specific preambles are divided between CSI-RS beams in thecorresponding PRACH occasions, the number of available preambles perbeam may be determined by the K preambles/number of beams.

If the preambles are partitioned in SS-block specific manner, the UE mayindicate preferred SS-block but not the preferred individual DL TX beamto gNB.

The network may configure mapping/partitioning PRACH preamble resourcesto SS-blocks and/or to individual beams. A UE may determine the usedpartitioning of PRACH preambles, as much as possible, e.g. based on thePRACH configuration.

Beam-specific PRACH configurations may be configurable when a gNB usesanalog RX beamforming. In that case, when a UE sends, for example, apreamble in a beam-specific time/frequency slot associated with one ormultiple SS Block transmissions, then the gNB may use the appropriate RXbeamforming when receiving the preamble in that time/frequency slot anduse the corresponding DL beam when transmitting the RAR. Hence,beam-specific PRACH configurations may allow the gNB to direct its Rxbeamforming in the direction of the same beam when monitoring theassociated PRACH resources.

Example Subsequent transmissions: In the multi-beam RACH scenario,thanks to the mapping between DL SS beams and PRACH configuration, e.g.time/frequency slot and possibly preamble partitioning, a UE may beunder the coverage of a given DL beam or at least a subset of them in acell. That may enable the network to send a RAR in this best DL beamand/or perform a more optimized beam sweeping procedure e.g. nottransmitting the same RAR message in possible beams (e.g. transmittingthe RAR in a single beam as in the figure below) as illustrated in FIG.33.

FIG. 33 illustrates an example of an RA procedure with multi-beam; a UEdetects the second SS blocks and thereby transmits a preamble on a RACHresource corresponding to the second SS block to inform gNB of thepreferred beam. gNB responds with a RAR using the beam that the UEprefers.

Example Contention-free RACH with multi-beam operations: NR may supportthe contention-free scenarios in a way to provide a dedicated RACHresource for the preamble transmission as in LTE for handover, DL dataarrival, positioning and obtaining timing advance alignment for asecondary TAG. For the handover case, a UE may be configured to measureon one or more SS blocks or other RS in a neighboring cell. If one ofthe neighboring cell SS-block measurements triggers a handover request,the source gNB may signal a preferred beam index in a handover requestto the target gNB. The target gNB in turn may provide a beam-specificdedicated RACH resource (including preamble) in the handover command. Inan example, the target gNB may provide a set of dedicated resources e.g.one for at least one SS-block in the handover command. The UE then maytransmit Msg1 using the dedicated preamble corresponding to thepreferred DL beam in the target cell.

In an example, as shown in FIG. 15 and/or FIG. 16, a distributed radioaccess network entity (e.g. distributed unit, DU, gNB-DU, and/or thelike) may detect one or more radio link state indications indicatingthat a wireless device (e.g. UE) may experience a radio link failurefrom the distributed radio access network entity and/or that thedistributed radio access network entity may lose and/or have lost aconnection with the wireless device. The wireless device may beconfigured to be served by the distributed radio access network. The oneor more radio link state indications may be one or more events that anumber of downlink packet retransmissions (e.g. RLC layer packetretransmissions) reaches a threshold number of downlink packetretransmissions. The one or more radio link state indications may be oneor more events that the distributed radio access network entity does notreceive a (periodic) channel quality indication (CQI) report from thewireless device at least for a first threshold time duration. The one ormore radio link state indications may be one or more events that thedistributed radio access network entity does not receive at least onepacket from the wireless device at least for a second threshold timeduration. The one or more radio link state indications may be one ormore events that the distributed radio access network entity does notreceive a (periodic) precoding matrix indicator (PMI) report and/or a(periodic) rank indicator (RI) from the wireless device at least for athird threshold time duration.

In an example, the distributed radio access network entity may receiveat least one of the threshold number of downlink packet retransmissions,the first threshold time duration, the second threshold time duration,and/or the third threshold time duration from a central radio accessnetwork entity (e.g. central unit, CU, gNB-CU, and/or the like). In anexample, the threshold number of downlink packet retransmissions, thefirst threshold time duration, the second threshold time duration,and/or the third threshold time duration may be pre-configured to thedistributed radio access network entity.

In an example, the one or more radio link state indications may be oneor more physical layer link problems and/or one or more MAC/RLC layerlink problems between the distributed radio access network entity andthe wireless device, the problems detected by the distributed radioaccess network entity.

In an example, the distributed radio access network entity may transmit,to a central radio access network entity, a first message comprising aradio link state information for the wireless device. The first messagemay be transmitted via an F1 interface between the distributed radioaccess network entity and the central radio access network entity. In anexample, the first message may comprise a UE context release requestmessage, a UE context modification required message, a UE statusinformation message, and/or an F1 message comprising radio link staterelated information of the wireless device. The distributed radio accessnetwork entity may determine one or more elements of the first messageat least based on the detecting of the one or more radio link stateindications. In an example, the radio link state information may beassociated with one or more serving cells of the distributed radioaccess network entity. The first message may further comprise one ormore cell identifiers of the one or more serving cells associated withthe radio link state information.

The radio link state information may comprise at least one of: anindication indicating that a number of downlink packet retransmissions(e.g. RLC layer packet retransmissions) reaches to the threshold numberof downlink packet retransmissions; an indication indicating that thedistributed radio access network entity does not receive a (periodic)channel quality indication report from the wireless device at least fora first threshold time duration; an indication indicating that thedistributed radio access network entity does not receive a soundingreference signal (SRS) from the wireless device at least for a certainthreshold time duration; an indication indicating that the distributedradio access network entity does not receive at least one packet fromthe wireless device at least for the second threshold time duration; anindication indicating that the distributed radio access network entitydoes not receive a (periodic) precoding matrix indicator (PMI) reportand/or a (periodic) rank indicator (RI) from the wireless device atleast for the third threshold time duration; one or more indicationsindicating one or more physical layer link problems and/or one or moreMAC/RLC layer link problems between the distributed radio access networkentity and the wireless device; and/or the like.

In an example, the radio link state information may comprise a radiolink failure indication explicitly indicating that a radio link of thewireless device may be failed (e.g. as a result that a primary cell ofthe wireless device has a radio link problem (e.g. connection failure)).In an example, the radio link state information may comprise aconnection loss indication explicitly indicating that the distributedradio access network entity may lose and/or have lost a connection withthe wireless device. The distributed radio access network entity maydetermine that a radio link of the wireless device is failed and/or thata connection with the wireless device is lost at least based on thedetecting of the one or more radio link state indications indicatingthat the wireless device may experience a radio link failure from thedistributed radio access network entity.

In an example, the central radio access network entity may determine aradio link failure of the wireless device and/or may determine aconnection loss with the wireless device at least based on one or moreelements of the first message (e.g. as a result that the radio linkstate information of the first message indicates that a primary cell ofthe wireless device has a radio link problem (e.g. connection failure)).The central radio access network entity may start one or more timers atleast based on one or more elements of the radio link state informationreceived via the first message. In an example, if the central radioaccess network entity receives, from the distributed radio accessnetwork entity, an indication indicating that a radio link failurerelated situation and/or a connection loss related situation (e.g.situations indicated via the one or more elements of the radio linkstate information) is resolved and/or recovered, the central radioaccess network entity may stop at least one of the one or more timers.If one or more of the one or more timers are expired, the central radioaccess network entity may determine a radio link failure of the wirelessdevice and/or may determine a connection loss with the wireless device.

In an example, the central radio access network entity may determine aradio link failure of the wireless device and/or may determine aconnection loss with the wireless device at least based on detectingthat the central radio access network entity (e.g. PDCP layer) does notreceive at least one packet from the wireless device at least for athreshold time duration.

In an example, in response to determining a radio link failure of thewireless device and/or determining a connection loss with the wirelessdevice, the central radio access network entity may release one or morewireless device contexts comprising one or more data radio bearers, oneor more bearers, one or more protocol data unit sessions (PDU sessions),one or more QoS flows, one or more security related parameters, one ormore configuration parameters for the wireless device, and/or the like.

In an example, in response to determining a radio link failure of thewireless device and/or determining a connection loss with the wirelessdevice, the central radio access network entity may transmit, to thedistributed radio access network entity, a second message configured torequest a first wireless device context release for the wireless device.The second message may be transmitted via an F1 interface between thedistributed radio access network entity and the central radio accessnetwork entity. In an example, the second message may comprise a UEcontext release command message, a UE context modification requestmessage, and/or an F1 message indicating release of UE context of thewireless device. One or more elements of the second message may bedetermined at least based on one or more elements of the radio linkstate information of the first message. The second message may comprisea wireless device identifier (e.g. C-RNTI, IMSI, TMSI, UE FLAP ID,gNB-CU UE F1AP ID, gNB-DU UE F1AP ID, and/or an identifier identifyingthe wireless device at least at the distributed radio access networkentity) of the wireless device, a cause of requesting a first wirelessdevice context release, and/or the like. The cause of requesting a firstwireless device context release may comprise a radio link failure of thewireless device and/or a connection loss with the wireless device.

In an example, in response to receiving the second message, thedistributed radio access network entity may release a first wirelessdevice context of the wireless device. The first wireless device contextmay comprise one or more bearers (one or more logical channels), one ormore security information, one or more configuration parametersassociated with the wireless device, and/or the like. In an example, thedistributed radio access network entity may transmit, to the centralradio access network entity, an indication message indicating that thedistributed radio access network entity released (removed) one or moreof the first wireless device context in response to the second message.

In an example, if the distributed radio access network entity determinesa radio link failure of the wireless device and/or a connection losswith the wireless device at least based on the one or more radio linkstate indications, the distributed radio access network entity mayrequest, to the central radio access network entity, releasing one ormore elements of the first wireless device context for the wirelessdevice. The distributed radio access network entity may transmit a causeof requesting the release. The cause may be at least one of a radio linkfailure of the wireless device and/or a connection loss with thewireless device.

In an example, in response to determining a radio link failure of thewireless device and/or determining a connection loss with the wirelessdevice, the central radio access network entity may transmit, to a corenetwork entity (e.g. AMF, access and mobility management function), athird message configured to request a second wireless device contextrelease for the wireless device. In an example, the third message may bea UE context release request message (wireless device context releaserequest message). The third message may be transmitted via an interfacebetween the central radio access and the core network entity (e.g. an NGinterface). In an example, the third message may comprise a wirelessdevice identifier (e.g. C-RNTI, IMSI, TMSI, AMF UE NGAP ID, gNB UE NGAPID, gNB-CU UE F1AP ID, gNB-DU UE F1AP ID, and/or an identifieridentifying the wireless device at least at the core network entity) ofthe wireless device, a cause of requesting a second wireless devicecontext release, and/or the like. The cause of requesting a secondwireless device context release may comprise a radio link failure of thewireless device and/or a connection loss with the wireless device.

In an example, in response to receiving the third message, the corenetwork entity may release a second wireless device context associatedwith an interface connection between the central radio access networkentity and the core network entity for the wireless device (e.g. NGconnection associated with the wireless device). The second wirelessdevice context (for the wireless device) released by the core networkentity may comprise one or more bearers (e.g. one or more NG bearers),one or more protocol data unit (PDU) sessions, one or more QoS flows,one or more security information, one or more configuration parametersassociated with the wireless device, and/or the like. In an example, thecore network entity may transmit, to the central radio access networkentity, an indication message indicating that the core network entityreleased (removed) one or more of the second wireless device context asa response to the third message.

In an example, a distributed radio access network entity may transmit,to a central radio access network entity, a first message comprising aradio link state information for a wireless device. The radio link stateinformation may comprise at least one of: an indication indicating thata number of downlink packet retransmissions reaches to a thresholdnumber of downlink packet retransmissions; an indication indicating thatthe distributed radio access network entity does not receive a(periodic) channel quality indication report from the wireless device atleast for a first threshold time duration; an indication indicating thatthe distributed radio access network entity does not receive at leastone packet from the wireless device at least for a second threshold timeduration; and/or a radio link failure indication. The distributed radioaccess network entity may receive, from the central radio access networkentity, a second message configured to request a first wireless devicecontext release for the wireless device. The second message may bedetermined at least based on one or more elements of the radio linkstate information.

In an example, the radio link state information may be associated with acell identifier of a serving cell of the distributed radio accessnetwork entity. The central radio access network entity may determine aradio link failure of the wireless device and/or a connection lose forthe wireless device at least based on one or more elements of the radiolink state information received via the second message. The centralradio access network entity may transmit, to a core network entity, athird message configured to request a second wireless device contextrelease for the wireless device. The second wireless device contextrelease may be at least associated with an interface connection betweenthe central radio access network entity and the core network entity forthe wireless device. In an example, the first wireless device contextrelease may be associated with releasing a wireless device context ofthe wireless device. The wireless device context may comprise at leastone of: one or more data radio bearers; one or more logical channels;one or more security configuration parameters; and/or one or moreinformation associated with the wireless device.

Distributed Unit Configuration Update

In an example, a base station may consider radio resource condition andtraffic status to configure wireless device control parameters, resourceconfiguration parameters, and/or cell configuration parameters. In thefunctional split scenario, a base station central unit configureswireless device control parameters, and a base station distributed unitmay monitor radio resource condition and traffic status of thedistributed unit. In an existing technology, a base station CU may haveless information of lower layer radio condition (e.g. physical layer,MAC layer, RLC layer, and/or the like). When a central unit configurewireless device configuration parameters, resource parameters, and/orcell configuration parameters, the lack of lower layer radio conditionand/or status information may cause inappropriate configurations, whichmay decrease cellular system performance. In an example, the lack oflower layer status information may cause a central unit to configuresystem and/or wireless device configuration parameter inappropriate forcurrent radio and/or traffic status. The inappropriate configuration maycause increased call dropping ratio, packet error rate, and/or packettransmission delay, and further may decrease communication reliabilityand/or increase data transmission latency.

Example implementation of embodiments may support a base stationdistributed unit to inform a base station central unit of lower layerradio condition information and/or traffic status of cells. Exampleimplementation of embodiments may support a base station distributedunit to request a base station central unit to modify radio and/orwireless device configuration parameters (e.g. release/modify bearers)based on lower layer radio condition information and/or traffic statusof cells. In an example embodiment, a distributed unit (DU) may request,to a central unit (CU), a distributed entity modification for a wirelessdevice based on detecting one or more network system state and/or one ormore radio network state associated with the distributed unit. Thecentral unit may transmit, to the distributed unit, a response messagefor the request and/or may modify one or more network configurations forthe wireless device at least based on the request. Exampleimplementation of embodiments may increase communication reliabilityand/or reduce data transmission latency of wireless communicationsystems.

In an example embodiment, a distributed radio access network entity (DU,distributed unit) may request, to a central radio access network entity(CU, central unit), a distributed entity modification for a wirelessdevice based on detecting one or more network system state and/or one ormore radio network state associated with the distributed radio accessnetwork entity. The central radio access network entity may transmit, tothe distributed radio access network entity, a response message for therequest and/or may modify one or more network configurations for thewireless device at least based on the request.

In an example, as shown in FIG. 17, FIG. 18, FIG. 19, and/or FIG. 20, adistributed radio access network entity may transmit, to a central radioaccess network entity, a first message configured to request adistributed entity modification for a wireless device. The first messagemay be transmitted via an F1 interface between the distributed radioaccess network entity and the central radio access network entity. Thefirst message may comprise at least one of a UE context modificationrequired message, a UE context release request message, and/or adistributed entity modification request message (e.g. gNB-DUmodification request, DU modification request). The first message maycomprise at least one of: one or more data radio bearer identifiers ofone or more data radio bearers for the wireless device that thedistributed radio access network requests to release, setup, and/ormodify; one or more logical channel identifiers (LCIDs) of one or morelogical channels for the wireless device that the distributed radioaccess network requests to release, setup, and/or modify; one or morebeam information (e.g. beam identifiers, beam index, synchronizationsignal block configuration information, reference signal configurationinformation, and/or the like) of one or more beams recovered by thewireless device; one or more beam information of one or more beamsserving the wireless device; one or more beam information of one or morebeams released by the wireless device; an indication parameterindicating that the wireless device changed one or more serving beams;and/or the like.

In an example, as shown in FIG. 17, if a distribute unit detects highload status (e.g. lack of radio resources, large data buffering status,high CPU employment, throttled CPU operation, high utilization of radioresources, lack of system memory, and/or the like), low radio channelquality (e.g. low RSRP/RSRQ, low quality of SRS received, low channelquality report (e.g. CQI report) from the wireless device, high packetretransmission rate, high packet transmission failure rate, and/or thelike) and/or the like of one or more cells employed for a first bearerof the wireless device, the distributed unit may request torelease/modify (e.g. release part (e.g. QoS flow) of the first bearer)the first bearer via the first message. In an example, the first bearermay comprise a data radio bearer (DRB) of the wireless device.

In an example, one or more beam information may comprise at least one ofa beam identifier, a beam index, a synchronization signal blockconfiguration information, a reference signal configuration information,a synchronization signal block scheduling information, a referencesignal configuration scheduling information, and/or the like.

In an example, the first message may comprise at least one of an uplinkradio resource measurement result measured by the distributed radioaccess network entity; an interference information associated with thewireless device (uplink interference measured by the distributed radioaccess network entity, downlink interference measured by the wirelessdevice); an interference information associated with one or more cellsof the distributed radio access network entity (uplink interferencemeasured by the distributed radio access network entity, downlinkinterference measured by the wireless device); one or more radio linkconfiguration changes; and/or the like.

In an example, the first message may comprise at least one or more radioconfiguration parameters for the wireless device, the one or more radioconfiguration parameters may be changed by the distributed radio accessnetwork entity and/or by the central radio access network entity. Thefirst message may be configured to request changing one or more of theone or more radio configuration parameters and/or to inform that one ormore of the one or more radio configuration parameters are changedand/or have been changed. The one or more radio configuration parametersmay comprise one or more MAC configuration parameters, one or more RLCconfiguration parameters, one or more physical layer configurationparameters, and/or the like.

In an example, the one or more radio configuration parameterstransmitted via the first message may comprise at least one of abcch-Config (broadcast control channel configuration parameter), apcch-Config (paging control channel configuration parameter), arlc-Config (RLC configuration parameter), a logicalChannelConfig(logical channel configuration parameter), a macMainConfig (MACconfiguration parameter), a sps-Config (semi-persistent schedulingconfiguration parameter), a rach-ConfigCommon (random accessconfiguration parameter), a prach-Config (physical layer random accessconfiguration parameter), a pdsch-ConfigCommon/a pdsch-ConfigDedicated(physical downlink shared channel configuration parameter), apusch-ConfigCommon/a pusch-ConfigDedicated (physical uplink sharedchannel configuration parameter), a pucch-ConfigCommon/apucch-ConfigDedicated (physical uplink control channel configurationparameter), a phich-Config (physical hybrid-ARQ indicator channelconfiguration parameter, a physical downlink control channelconfiguration parameter, a cqi-ReportConfg (channel quality indicatorreport configuration parameter, and/or the like.

In an example, the one or more radio configuration parameters maycomprise at least one of a PMI report configuration parameter, an RIreport configuration parameter), a schedulingRequestConfig (schedulingrequest configuration parameter), a soundingRS-UL-ConfigCommon/asoundingRS-UL-ConfigDedicated (sounding reference signal uplinkconfiguration parameter), an uplinkPowerControlCommon/anuplinkPowerControlDedicated (uplink power control configurationparameter), a p-Max (uplink maximum power configuration parameter), aphr-Config (power headroom report configuration parameter), anantennaInfoCommon/an antennaInfoDedicated (antenna configurationparameter), an ul-CyclicPrefixLength (uplink cyclic prefix configurationparameter), a tdd-Config (a time division duplex configurationparameter), a system information broadcast message configurationparameter, a channel state information report configuration parameter, aDMRS-Config (demodulation reference signal configuration parameter), asynchronization signal configuration parameter, a reference signalconfiguration parameter, a drx-Config (discontinuous receptionconfiguration parameter), a time alignment configuration parameter/atiming advance configuration parameter (e.g. time alignment timer,timing advance group identifier, timing advance group information,and/or the like), a RLC retransmission configuration parameter, a HARQconfiguration parameter (hybrid automatic repeat request configurationparameter), and/or the like.

In an example, the central radio access network entity may configure oneor more configuration parameters for the wireless device at least basedone or more elements of the first message. In response to the firstmessage, the central radio access network entity may release, setup,and/or modify one or more data radio bearers, one or more logicalchannels, one or more QoS flows, one or more PDU sessions, one or morelogical channels for the wireless device at least based on one or moreelements of the first message. In an example, if the first messageindicates a request to release/modify the first bearer of the wirelessdevice, the central unit may determine to release/modify the firstbearer based on the request of the first message. The central radioaccess network entity may configure one or more configuration parametersfor the wireless device, the one or more configuration parametersassociated with one or more elements of the first message.

In an example, the central radio access network entity may transmit, tothe distributed radio access network entity, a second message at leastin response to configuring the one or more configuration parameters forthe wireless device. The second message may be transmitted via an F1interface between the central radio access network entity and thedistributed radio access network entity. The second message may compriseone or more indications indicating at least one of: accepting one ormore elements of the first message; rejecting one or more elements ofthe first message; and/or confirming one or more elements of the firstmessage. The second message may comprise one or more configurationindications indicating that the distributed radio access network entityconfigures one or more configuration parameters for the wireless deviceat least based on one or more elements of the first message. The one ormore configuration indications may comprise a configuration indicationfor at least one of one or more elements of the first message. In anexample, the second message may comprise a UE context modificationconfirm message, a UE context modification request message, a UE contextrelease command message, and/or the like.

In an example, the central radio access network entity may transmit, tothe wireless device, a third message at least based on configuring theone or more configuration parameters for the wireless device at leastbased on one or more elements of the first message. The third messagemay comprise one or more RRC messages (radio resource control messages).The third message may comprise at least one of: one or more data radiobearer identifiers of one or more data radio bearers to release, setup,and/or modify; one or more logical channel identifiers (LCIDs) of one ormore logical channels to release, setup, and/or modify; one or more QoSflow identifiers of one or more QoS flows to release, setup, and/ormodify; one or more PDU session identifiers of one or more PDU sessionsto release, setup, and/or modify; one or more beam information (e.g.beam identifiers, beam index, synchronization signal block configurationinformation, reference signal configuration information, and/or thelike); one or more beam utilization information (e.g. beam informationof beams for the wireless device to monitor, utilize, be restricted toutilize, remove, and/or the like); beam priority information to use;and/or the like. In an example, the third message comprise one or moreelements of the one or more radio configuration parameters of the firstmessage. The third message comprise one or more configuration parameterconfigured at least based on one or more elements of the one or moreradio configuration parameters of the first message.

In an example, the distributed radio access network entity may decodethe third message transmitted to the wireless device, and/or maydetermine one or more radio link configurations at least based on one ormore elements of the third message.

In an example, the distributed radio access network entity may configureone or more elements of the first message and/or may transmit the firstmessage at least based on detecting one or more radio network states.The one or more radio network states may comprise at least one of: aload state (physical resource block usage state and/or hardware loadstate, e.g. cpu, processor, ram, memory, system bus load state) of thedistributed radio access network entity; a radio load state of one ormore cells of the distributed radio access network entity; an averageuplink/downlink buffer state information of the wireless device; a timealignment timer expiration; a channel state information received fromone or more wireless device (e.g. a channel quality information, aprecoding matrix indicator, a rank indicator); an uplink radio resourcemeasurement result measured by the distributed radio access networkentity; an interference information associated with the wireless device(uplink interference measured by the distributed radio access networkentity, downlink interference measured by one or more wireless device);an interference information associated with one or more cells of thedistributed radio access network entity (uplink interference measured bythe distributed radio access network entity, downlink interferencemeasured by one or more wireless device); one or more radio linkconfiguration changes; and/or the like.

In an example, a distributed radio access network entity may transmit,to a central radio access network entity, a first message configured torequest a distributed entity modification for a wireless device. Thefirst message may comprise at least one of: one or more data radiobearer identifiers of one or more data radio bearers to be released; oneor more data radio bearer identifiers of one or more data radio bearersto be modified; one or more radio configuration parameters to bechanged; one or more beam information of one or more beams recovered bythe wireless device; one or more beam information of one or more beamsserving the wireless device; one or more beam information of one or morebeams released by the wireless device; an indication parameterindicating that the wireless device changed one or more serving beams;and/or the like. The distributed radio access network entity mayreceive, from the central radio access network entity, a second messagein response to the first message. The second message may comprise anindication indicating at least one of: accepting one or more elements ofthe first message; rejecting one or more elements of the first message;and/or confirming one or more elements of the first message.

In an example, the distributed radio access network entity may transmit,the first message based on at least one of: a load state (PRB usagestate, hardware load state, and/or the like) of the distributed radioaccess network entity; a radio load state of one or more cells of thedistributed radio access network entity; an average uplink/downlinkbuffer state information of the wireless device; a time alignment timerexpiration; a channel state information received from the wirelessdevice (e.g. a channel quality information, a precoding matrixindicator, a rank indicator); an uplink measurement result by thedistributed radio access network entity; an interference informationassociated with the wireless device; an interference informationassociated with one or more cells of the distributed radio accessnetwork entity; and/or one or more radio link configuration changes.

In an example, the central radio access network entity may transmit, tothe wireless device, a third message comprising one or more radioresource control parameters at least based on one or more elements ofthe first message. The one or more radio resource control parameters maycomprise at least one of: one or more data radio bearer identifiers ofone or more data radio bearers to be released; one or more data radiobearer identifiers of one or more data radio bearers to be modified;and/or one or more radio link configuration parameters to be changed.The distributed radio access network entity may decode the thirdmessage, and/or may determine one or more radio link configurations atleast based on one or more elements of the third message.

Distributed Unit Status Information

In an example, a base station may consider radio resource condition andtraffic status to configure wireless device control parameters, resourceconfiguration parameters, and/or cell configuration parameters. In thefunctional split scenario, a base station central unit configureswireless device control parameters, and a base station distributed unitmay monitor radio resource condition and traffic status of thedistributed unit. In the functional split scenario, a base stationcentral unit configures wireless device control parameters, and a basestation distributed unit may monitor grant free resources (configuredresources) and/LAA cell status of the distributed unit.

In an implementation of an existing technology, a base station CU mayhave less information of lower layer radio condition (e.g. physicallayer, MAC layer, RLC layer, and/or the like). When a central unitconfigure wireless device configuration parameters, resource parameters,and/or cell configuration parameters, the lack of lower layer radiocondition (e.g. configured grant resource radio channel status, grantfree resource radio channel status, SPS resource radio channel status,LAA cell channel status and/or the like) and/or status information (e.g.configured grant resource utilization status, grant free resourceutilization status, SPS resource status, LAA cell status information,and/or the like) may cause inappropriate configurations, which maydecrease cellular system performance. In an example, the lack of lowerlayer status information may cause a central unit to configure systemand/or wireless device configuration parameter inappropriate for currentradio and/or traffic status. The inappropriate configuration may causeincreased call dropping ratio, packet error rate, and/or packettransmission delay, and further may decrease communication reliabilityand/or increase data transmission latency.

Example implementation of embodiments may support a base stationdistributed unit to inform a base station central unit of lower layerradio condition information and/or traffic status of cells. Exampleimplementation of embodiments may support a base station distributedunit to transmit status information of configured grant resource status,grant free resource status, SPS resource status (e.g. utilizationinformation, collision status, failure status, channel quality). Exampleimplementation of embodiments may support a base station distributedunit to transmit status information of LAA cell status information (e.g.LBT failure status, channel quality status, collision status, activatedUE information on LAA cell, and/or the like).

In an example embodiment, a distributed unit may transmit, to a centralunit, a grant free (e.g. configured grant type 1/2, configured grant,SPS) resource utilization information of a serving cell served by thedistributed radio access network entity. The central unit may configureand/or reconfigure one or more grant free resources and/or wirelessdevice resource configuration parameters at least based on the grantfree resource utilization information. The central unit may request, tothe distributed unit, a grant free resource utilization informationreport with an event based condition for the report and/or a periodicityto report. In an example embodiment, a distributed unit may transmit, toa central unit, a radio resource status information (e.g. LBT failurestatus, channel quality status, collision status, activated UEinformation, and/or the like) of a licensed assisted access (LAA) cellserved by the distributed unit. The central unit may configure and/orreconfigure one or more configuration parameters for the licensedassisted access cell at least based on the radio resource statusinformation. The central unit may request, to the distributed unit, aradio resource status information report for a licensed assisted accesscell with an event based condition for the report and/or a periodicityto report. Example implementation of embodiments may increasecommunication reliability and/or reduce data transmission latency ofwireless communication systems.

A new radio (NR) may support an uplink (UL) transmission without a ULgrant, referred to as a grant-free (GF) UL transmission, for one or moreservice types, e.g., ultra-reliable low latency communications (URLLC).A base station in the NR, referred to as a gNB, may configure the timeand frequency radio resource(s) for the GF UL transmission. A UEconfigured by the gNB to use the GF UL radio resources may transmit oneor more data packets without a UL grant, which may result in reducingthe signaling overhead comparing with a grant-based (GB) ULtransmission. Such a service type that has strict requirements,especially in terms of latency and reliability such as URLLC, may be acandidate for which a UE may use the GF UL transmission.

The GF UL transmission may support multiple user equipments (UEs)accessing the same radio resources in order to achieve lower latency andlower signaling overhead than a GB UL transmission. A GF radio resourcepool may be defined as a subset of radio resources from a common radioresource set (e.g. from all uplink shared channel radio resources). Theradio resource pool may be used to allocate exclusive or partiallyoverlapped radio resources for GF UL transmissions in a cell or toorganize frequency/time reuse between different cells or parts of a cell(e.g. cell-center and cell-edge).

If a gNB configures multiple UEs with the same GF radio resource pool,there may be a collision between two or more UEs on their GF ULtransmission. The collision at the same GF radio resources may beavoidable based on UE specific demodulation reference signal (DMRS)parameters that are distinguishable at the gNB, e.g., the root index ifZadoff-Chu (ZC) sequences are adopted, cyclic shift (CS) index, TDM/FDMpattern index if any, orthogonal cover code (OCC) sequences or index.The gNB may configure the UE specific DMRS parameters along with thetime/frequency radio resources for the UE.

In an example, FIG. 34 is two examples of DMRS design with 4 UEsmultiplexed on each DMRS symbol. The DMRS of 4 UEs are plotted withdifferent patterns, respectively. Figure xxx considers an example with 2DMRS symbols out of 14 orthogonal frequency-division multiplexing (OFDM)symbols. Top of FIG. 34 is a comb pattern used to divide resourceelements (REs) in one symbol into DMRS RE groups, and a UE occupies agroup of REs to transmit its DMRS. In this way, the DMRS of multiplexedUEs may be orthogonal to guarantee the accuracy of channel estimationand related measurements. Bottom of FIG. 34 is a Zadoff-Chu (ZC)sequence with different cyclic shifts used to accommodate multiple UEs'DMRSs in the same OFDM symbol. In this way, the channel impulse response(CIR) of multiplexed UEs may be effectively delayed and be separated intime domain, which may facilitate channel estimation and measurements.Note that the location of DMRS in Top of FIG. 34 follows legacy LTEdesign, which is an example only. For URLLC, DMRS may be put on thefirst 2 OFDM symbols.

To identify a UE ID from the collision over the same GF radio resourcepool, instead of DMRS, a gNB may use a preamble sequence that may betransmitted together with the PUSCH data. The preamble may be designedto be reliable enough and to meet the detection requirement of aservice, e.g., URLLC. FIG. 35 is an example of the basic procedure of GFUL transmission with a preamble may be that a UE may start a GF ULtransmission in the configured radio resources when there is a packet inthe UE buffer. The UE may transmit a preamble together with the datablock in the first step and receive a response in the second step. Thedata may be repeated K times depending on a gNB configuration. Thepreamble may not be repeated as long as it is reliable enough. Theresponse from a gNB may be a UL grant or a dedicated ACK/NACKtransmitted in the downlink control information (DCI).

For UEs configured with a GF radio resource pool, a preamble sequencemay be uniquely allocated to a UE with the assumption that the number ofUEs sharing the same GF radio resources is smaller than the number ofavailable preamble sequences. This may be the typical case consideringthat the number of URLLC UEs in a cell may not be large. In addition,the gNB may configure different GF radio resources for different sets ofUEs such that the preamble sequences may be reused in different GF radioresources.

To have reliable detection performance, the preamble sequences may bemutually orthogonal, e.g. cyclic shifts of a ZC root sequence. Since thepreamble sequence is transmitted together with data, it may be reused asthe reference signals for the data demodulation. To ensure a reliable UEID detection based on the preamble sequence, relatively high number ofREs may be needed for the preamble transmission. To have reliablepreamble detection performance while having balanced preamble overheadfor GF and a low impact on other UEs, a gNB may configure a number ofOFDM symbols for preamble transmission in time domain and a bandwidth infrequency domain, depending on whether DMRS may provide reliabledetection performance. There may be following possible configurationoptions in case the preamble bandwidth is larger than the datatransmission bandwidth,

Two set of GF UEs may share the same preamble transmission bandwidth,but different data transmission bandwidth, e.g., the preambles of bothset of UEs are multiplexed in the same radio resources.

For a target UE, the preamble REs that are within the bandwidth for GFUL data transmission may be reused as the reference signals for GF datademodulation. The preambles that are transmitted outside of GF databandwidth may be orthogonally multiplexed with the DMRS of a GB UE. Thismay reduce the impact to GB UEs.

FIG. 36 illustrate an example. In top of FIG. 36, one mini-slot contains4 OFDM symbols and gNB configures two OFDM symbols for the preambletransmission. In bottom of FIG. 36, 3 OFDM symbols are contained in onemini-slot, and the preamble is configured to transmit in 1 OFDM symbol,but in larger transmission BW than the data transmission.

For the GF UL transmission, a gNB may support a K-repetition of the sametransport block (TB) transmission over the GF radio resource pool untilcertain conditions are met. The UE may continue the repetitions upto Ktimes for the same TB until one of the following conditions is met: Ifan UL grant is successfully received for a slot/mini-slot for the sameTB; the number of repetitions for that TB reaches K; and/or othertermination condition of repetition may apply.

The number of maximum repetitions, K, may be a configurable parameterthat may be UE-specific, and/or cell-specific.

A mini-slot or a symbol may be a unit of the K-repetition. A network mayconfigure the number of this repetition and the radio resource inadvance. The network may assume a set of initial transmission and therepetition as one amount of the transmission. The network may not berequired to prepare the case of only initial transmission or onlyrepetition. One may call the set of initial transmission and thisrepetition as extended TTI. These repetitions may not be required to becontiguous in time. If transmissions are contiguous, it may allowcoherent combining. If transmissions are not contiguous, it may allowtime diversity.

When the GF UL transmission of two UEs collides in the same GF radioresource pool, a gNB may fail to detect both UEs' data. When the two UEsretransmit the data without UL grants, the two UEs may collide again. Insuch a case, hopping may be a way to solve the collision problem whenradio resources are shared by multiple UEs. Hopping may randomize thecollision relationship between UEs within a certain time interval, thusavoiding persistent collision. It may bring a diversity gain on thefrequency domain. A UE-specific hopping pattern may be pre-configured bya gNB or obtained via some known UE-specific ID. FIG. 37 is an exampleof a UE-specific hopping pattern.

There may be many factors considered for the hopping pattern design,such as the number of resource units (RUs), the max number of UEssharing the same RU, the recently used RU index, the recent hoppingindex or the current slot index, the information indicating recentlyused sequence, hopping pattern or hopping rule, etc. The sequencedescribed above may be a DMRS, a spreading sequence, or a preamblesequence that may be UE-specific. FIG. 38 shows examples of GF resourceindex and configuration parameters.

The gNB may support to switch between GF and GB UL transmissions tobalance resource utilization and delay/reliability requirements ofassociated services. The GF UL transmission may be based on asemi-static resource configuration that may be beneficial to reducelatency. Such a pre-defined resource configuration may be hard tosatisfy all potential services or packet sizes. The overhead maysometimes be large, and the packet size for a service, such as URLLC,may be variable. If a UE's data packet collides with other UE's packets,a re-attempt to access GF radio resources may not achieve the servicerequirements. In such cases, switching from GF to GB UL transmissionsmay be beneficial.

FIG. 39 shows an example of uplink resource selection based on datasize.

To support the switching between GF and GB UL transmissions, the initialtransmission on the pre-configured GF radio resources may include UEidentification (ID), for example, explicit UE ID information (e.g.C-RNTI) or implicit UE information such as a DMRS cyclic shift (assuminguse of ZC sequences) specific signature. To inform a gNB of whether theUE has remaining data to transmit, the UE may include buffer statusreporting (BSR) with the initial data transmission. If a gNBsuccessfully decodes data transmitted by a UE and determines that the UEhas remaining data to transmit (e.g. from a BSR report), the gNB mayswitch scheduling for UE from GF to GB UL transmissions. If a gNB failsto decode data transmitted by the UE but successfully detects the UE IDfrom the uniquely assigned sequence (e.g., preamble and/or DMRS), thegNB may switch scheduling for UE from GF to GB UL transmissions. The ULgrant for subsequent data transmissions may be with CRC scrambled by theUE C-RNTI (may be determined either by explicit signaling in the initialtransmission or implicitly by the DMRS cyclic shift). In an example,FIG. 40 is an example of UE information request and response procedure.

One of the termination conditions for the K-repetitions may be areception of a UL grant which schedules a UL (re)transmission for thesame TB. A gNB may assign dedicated resources for retransmission inorder to ensure the TB is delivered within the latency budget. Thisbehavior may be classified as scheduling switching from GF to GBoperation. In this case, a UE may need to link the received grant withthe transmitted TB in order to understand which TB to be retransmittedin case there are multiple ongoing transmission processes at the UE. Forthese purposes, the UE and gNB may have the same notion of TB counting.

For the GF operation, the TB counting may not be possible if a gNB maynot detect some TBs due to collisions. In order to make an associationbetween a DCI with a TB, there may be several options. If there is noother transmission process at the UE side, it may directly associate theDCI with a TB which is being transmitted. If there are at least twodifferent TBs, a UE may deduct that the DCI is for a particular TB byapplying an implicit linkage assuming only one TB is transmitted in onetransmission interval. In this case, if the interval between detected UEtransmission and a grant is fixed, it may unambiguously determine whichTB may be retransmitted. If the timing between a detected transmissionand a retransmission grant is not preconfigured, an explicit indicationof the retransmitted TB may be carried by DCI. If a UE detects that agrant for one TB overlaps with transmission of another ongoing TB, theUE may assume precedence of the grant comparing to the grant-freeretransmissions. If a grant is received for a new TB (e.g. for aperiodicCSI reporting) and overlaps with the GF UL transmissions, the GFtransmissions may be dropped in the resources. Alternatively, aprioritization rule whether to transmit a triggered report or GF datamay be introduced depending on priority of the associated services. Forexample, if URLLC services is assumed, then the CSI reporting may bedropped in this example.

Another repetition termination condition may be to use a dedicatedPHICH-like channel for early termination. For this option, the PHICHdefined in LTE may be used as an acknowledge indicator. In LTE, thePHICH for a UE may be determined based on the physical resource block(PRB) and cyclic shift of the DMRS corresponding to the UE's PUSCHtransmission. Similar design principle may be reused in the NR. Such aPHICH-like channel may optimize the control channel capacity and systemcapacity. If a gNB has successfully received a TB, the gNB may obtainthe corresponding information about this transmission, such as the UEID, the resource used for carrying this transmission, the DMRS used forthis transmission, etc. The physical resources may be shared amongmultiple UEs who may have their own unique identifiers (e.g., DMRS) usedin the GF radio resource pool. Therefore, even for GF UL transmission,if the gNB has successfully received a TB, a unique PHICH may bedetermined.

Using a sequence based signal may be used for early termination ofK-repetition. In this case, a sequence based signal may be transmittedto inform the UE to terminate the repetition of transmission. In thiscase, the signal may be transmitted when a gNB successfully decodes aTB. The UE may perform a simple signal detection for the presence orabsence to decide whether to continue the repetitions or not.

A gNB may switch from GF to GB UL transmissions in order to solve a GFradio resource shortage problem. In an example, some UEs whose delayrequirements are not strict may use the GF radio resource to transmitdata. A gNB may measure the status of the GF UL radio resourceutilization based on statistics with respect to resource utilization,load, etc and set up a threshold policy to dynamically balance load orresource utilization of the GF UL radio resource. If the resource usagestatistic of the GF UL radio resource exceeds the predefined threshold,it may be beneficial to switch some UEs from the GF UL radio resource tothe GB UL radio resource, which may decrease the resource collision.

The GF resource pool configuration may not be known to UEs. It may onlyneed to be coordinated between different cells for interferencecoordination. If the GF resource pools are known to UEs, those may besemi-statically configured by UE-specific RRC signaling ornon-UE-specific RRC signaling. The RRC signaling for GF radio resourceconfiguration may include at least one or more parameters indicating GFtime/frequency radio resources, DMRS parameters, a modulation and codingscheme (MCS) or equivalently a transport block size (TBS), Number ofrepetitions K, and/or power control parameters.

A UE may need to know all necessary parameters for UL grant-freetransmission before transmitting on the resource. For this, not only RRCsignaling, but also the use of L1 signaling may be useful. For example,RRC signaling may configure the necessary parameters of GF ULtransmission to the UE, and L1 signaling may adjust, modify, update,activate, and/or deactivate these parameters. The L1 signaling may be aPDCCH, similar to the signaling used for LTE UL semi-persistentscheduling (SPS).

The MCS may be indicated by the UE within the grant-free data. In anexample, in order to avoid the blind decoding of MCS indication, thelimited number of MCS levels may be pre-configured by a gNB, e.g., Kbits may be used to indicate MCS of grant-free data, where K may be assmall as possible. The number of REs used to transmit MCS indication ina resource group may be semi-statically configured. In the GF operation,there may be one common MCS predefined for all UEs. In this case, theremay be a tradeoff between a spectrum efficiency and decodingreliability, e.g., the spectrum efficiency may be reduced if a low levelof MCS is used, while the data transmission reliability gets higher. TheNR may predefine a mapping rule between multiple time/frequencyresources for UL grant-free transmission and MCSs. In an example, a UEmay select an appropriate MCS according to a DL measurement andassociated time/frequency resources to transmit UL data. In this way, UEmay choose a MCS based on the channel status and increase the resourceutilization.

Once the GF UL transmission parameters are configured, a GF ULtransmission may be activated in different ways. The need for L1activation signaling may depend on actual service types, and the dynamicactivation (e.g, activation via L1 activation) may not be supported inthe NR or may be configurable based on service and trafficconsiderations.

In an example, both activation schemes with and without L1 activationsignaling may be supported. It may be up to a gNB to configure a UEwhich scheme may need to be used by considering, for example, trafficpattern, latency requirements, and other possible aspects. With the L1activation signaling, a UE may transmit data with the configured timefrequency radio resource after receiving L1 activation signaling fromgNB. If the L1 activation is not configured, UE may start a ULtransmission with the configured GF radio resource at any moment or in acertain time interval (which may be configured by RRC signaling orpre-defined) once the configuration is completed.

In an example, if a service that does not require high reliability andlatency may benefit from reduced signaling overhead and powerconsumption, then the L1 activation signaling may be beneficial incombination with L1 deactivation signaling to control network resourceload and utilization. When the L1 signaling is used, gNB may need toknow whether the UE correctly receives it. An acknowledgement to the L1signaling may be transmitted from a UE to a gNB.

For a delay sensitive service, however, the additional activationsignaling may cause additional delay and may lead to potential serviceinterruption/unavailability for the period of applying and requestingthe activation. In this case, a gNB may configure a GF operation suchthat the GF UL transmission is activated as soon as a GF radio resourceconfiguration and transmission parameters are configured.

There may be such a case that the GF radio resource is over-allocatedwhich may result in the waste of radio resources with few UEs. In thiscase, L1 signalling may be useful to reconfigure the GF UL radioresource and/or one or more GF transmission parameters. By allowing L1signaling-based reconfiguration, UEs may need to check downlink controlsignaling periodically whether the time/frequency resources for GF isthe same or not. This may increase the power consumption of UE, and theperiodicity to check the downlink control signaling may need to beconfigurable. In an example, if time/frequency radio resourceutilization is more important, the periodicity may be configured to beshort like every 1 minute or every radio frame. If the power consumptionis more important, the periodicity may be configured to be long likeevery 1 hour. The periodicity to check downlink control signaling mayneed to be allowed to be separated from the periodicity of GF ULtransmission, e.g., in order to shorten the latency. In an example, theperiodicity of GF radio resource may be less than 1 ms like 0.125 ms butthe periodicity to check downlink control signaling may be 1 minute or 1hour.

For deactivating the activated GF operation, L1 deactivation signalingmay be useful for all services in order to release resources as fast aspossible.

In an example embodiment, a distributed radio access network entity (DU,distributed unit) may transmit, to a central radio access network entity(CU, central unit), a grant free resource utilization information of aserving cell served by the distributed radio access network entity. Thecentral radio access network entity may configure and/or reconfigure oneor more grant free resources at least based on the grant free resourceutilization information. The central radio access network entity mayrequest, to the distributed radio access network entity, a grant freeresource utilization information report with an event based conditionfor the report and/or a periodicity to report.

In an example, a distributed radio access network entity may beconnected to a central radio access network entity. The two entities maybe connected via an F1 interface. A serving cell of the distributedradio access network entity may support one or more grant free resourcesfor one or more wireless devices. The one or more grant free resourcesmay be configured by the distributed radio access network entity and/orby the central radio access network entity. One or more of the one ormore grant free resources may be utilized for one or more types ofservices (e.g. selected at least based on a bearer type, a wirelessdevice subscription type, a slice type, a URLLC wireless device type, amachine type communication wireless device type, and/or the like).

In an example, the bearer (logical channel, data radio bearer, QoS flow,PDU session type) may be determined at least based on a QoS informationof the bearer (e.g QCI, 5QI, and/or ARP values). The slice type may bedetermined at least based on a slice identifier (e.g. NSSAI, S-NSSAI,and/or the like) of a slice. In an example, a wireless device may haveone or more slices for one or more services (e.g. vehicle communication,emergency service, mobile broadband service, push to talk service,streaming service, high priority services for high price subscribers,and/or the like).

In an example, the central radio access network entity may determine oneor more grant free resources (e.g. configured grant/SPS/configured granttype 1 or type 2/periodic resources) for the serving cell of thedistributed radio access network entity, and/or may transmit, to thedistributed radio access network entity, a first grant free resourceconfiguration information associated with the determined one or moregrant free resources. The first grant free resource configurationinformation may be associated with one or more types of services. Thefirst grant free resource configuration information may comprise atleast one of: a grant free resource scheduling information (e.g.frequency, timing, periodicity, scheduling interval, and/or the like), atype of services (e.g. bearer type, slice type, and/or the like) allowedto utilize the determined one or more grant free resources, a wirelessdevice type (e.g. wireless device subscription type, a URLLC wirelessdevice type, machine type communication wireless device type, and/or thelike) allowed to utilize the determined one or more grant freeresources, a numerology configuration information (e.g. which TTI isutilized for the determined one or more grant free resources), one ormore wireless device identifiers of one or more wireless devices allowedto utilize the determined one or more grant free resources (e.g. C-RNTI,SPSC-RNTI, IMSI, temporary wireless device identifier for a grant freeresource, and/or the like), a grant free resource configuration index,and/or the like. In an example, the first grant free resourceconfiguration information may be configured by the distributed radioaccess network entity.

In an example, as shown in FIG. 21 and/or FIG. 22, the central radioaccess network entity may transmit, to one or more wireless devices, oneor more radio resource control parameters (e.g. one or more radioresource control parameters) at least based on one or more elements ofthe first grant free resource configuration information. In an example,in response to receiving the first grant free resource configurationinformation, the distributed radio access network entity may configureone or more radio configuration parameters at least based on one or moreelements of the first grant free resource configuration information,and/or receive one or more packets from one or more wireless devices viaone or more of the determined one or more grant free resources. In anexample, the first grant free resource configuration information may beconfigured by the distributed radio access network entity.

In an example, the distributed radio access network entity maydetermine/configure one or more grant free resources for the servingcell of the distributed radio access network entity, and/or maytransmit, to the central radio access network entity, a second grantfree resource configuration information associated with the one or moregrant free resources determined/configured by the distributed radioaccess network entity. The second grant free resource configurationinformation may comprise at least one of: a grant free resourcescheduling information (e.g. frequency, timing, periodicity, schedulinginterval, and/or the like), a type of services (e.g. bearer type, slicetype, and/or the like) allowed to utilize the determined/configured oneor more grant free resources, a wireless device type (e.g. wirelessdevice subscription type, a URLLC wireless device type, machine typecommunication wireless device type, and/or the like) allowed to utilizethe determined/configured one or more grant free resources, a numerologyconfiguration information (e.g. which TTI is utilized for the configuredone or more grant free resources), one or more wireless deviceidentifiers of one or more wireless devices allowed to utilize thedetermined/configured one or more grant free resources (e.g. C-RNTI,SPSC-RNTI, IMSI, temporary wireless device identifier for a grant freeresource, and/or the like), a grant free resource configuration index,and/or the like.

In an example, the central radio access network entity may transmit, toone or more wireless devices, one or more radio resource controlparameters at least based on one or more elements of the second grantfree resource configuration information received from the distributedradio access network entity. In an example, the distributed radio accessnetwork entity may receive one or more packets from one or more wirelessdevices via one or more of the determined/configured one or more grantfree resources.

In an example, the central radio access network entity may transmit, tothe distributed radio access network entity, a fourth message configuredto request a grant free resource utilization information. In an example,the fourth message may be transmitted via the F1 interface. The fourthmessage may be a resource status request message. The fourth message maycomprise at least one of: one or more cell identifiers (e.g. global cellidentifier, physical cell identifier, unique cell identifier at least atthe distributed radio access network entity, and/or the like) of one ormore cells that the central radio access network entity requests a grantfree resource utilization information for, a triggering condition oftransmitting a grant free resource utilization information; and/or areporting periodicity of reporting a grant free resource utilizationinformation.

In an example, the triggering condition may comprise at least one of: amaximum grant free resource utilization level threshold (e.g. thedistributed radio access network entity may transmit a grant freeresource utilization information to the central radio access networkentity if a grant free resource utilization level of one or more cellsis same and/or higher than the maximum grant free resource utilizationlevel threshold); a minimum grant free resource utilization levelthreshold (e.g. the distributed radio access network entity may transmita grant free resource utilization information to the central radioaccess network entity if a grant free resource utilization level of oneor more cells is same and/or lower than the maximum grant free resourceutilization level threshold); a threshold number of uplink transmissioncollisions (e.g. the distributed radio access network entity maytransmit a grant free resource utilization information to the centralradio access network entity if a number of uplink transmissioncollisions of two or more wireless devices on one or more grant freeresources is same and/or larger than the threshold number of uplinktransmission collisions); and/or the like. The fourth message mayfurther comprise a period to measure a grant free resource utilizationstate to determine whether one or more elements of the triggeringcondition are satisfied.

In an example, the distributed radio access network entity may transmit,to the central radio access network entity, a first message comprising agrant free resource utilization information of the serving cell servedby the distributed radio access network entity. The first message may bedetermined and/or transmitted at least based on one or more elements ofthe fourth message. In an example, the first message may be transmittedvia the F1 interface. In an example, the first message may be a resourcestatus update message. In an example, one or more elements of the grantfree resource utilization information may be determined at least basedon the period to measure a grant free resource utilization state, theperiod received via the fourth message.

In an example, a first message may be triggered at least based on thetriggering condition and/or the reporting periodicity associated withone or more cells of the one or more cell identifiers received via thefourth message. In an example, if a ratio of used grant free resourcesof a serving cell of the distributed radio access network entity ishigher than 80% (a maximum grant free resource utilization levelthreshold: a maximum ratio of used grant free resources), thedistributed radio access network entity may transmit a grant freeresource utilization information for the serving cell to the centralradio access network entity. In an example, if a collision ratio ofgrant free resources of a serving cell of the distributed radio accessnetwork entity is lower than 5% (a minimum grant free resourceutilization level threshold: a minimum ratio of a collision ratio ofgrant free resources), the distributed radio access network entity maytransmit a grant free resource utilization information for the servingcell to the central radio access network entity.

In an example, the grant free resource utilization information of thefirst message may comprise at least one of: a ratio (e.g. a percentage)of used grant free resources (e.g. a numerator for the ratio may be anamount of grant free resources utilized by one or more wireless devicesamong configured grant free resources, and/or a denominator for theratio may be an amount of configured grant free resources for one ormore wireless devices); a collision ratio (e.g. a collision percentage)of grant free resources (e.g. a numerator for the collision ratio may bean amount of grant free resources simultaneously attempted to utilize bytwo or more wireless devices among configured grant free resources, adenominator for the collision ratio may be an amount of configured grantfree resources for one or more wireless devices, and/or a denominatorfor the collision ratio may be an amount of grant free resourcesutilized by one or more wireless devices among configured grant freeresources); an attempt collision ratio (e.g. an attempt collisionpercentage) of one or more wireless devices (e.g. a numerator for theattempt collision ratio may be a number of collided transmissionattempts of one or more wireless devices via grant free resources,and/or a denominator for the attempt collision ratio may be a number oftransmission attempts of one or more wireless devices via grant freeresources); and/or the like.

In an example, the ratio of used grant free resources, the collisionratio of grant free resources, and/or the attempt collision ratio of oneor more wireless devices may be comprise an indication indicating aratio level (e.g. high/medium/low,high/medium_high/medium/medium_low/low, and/or the like).

The grant free resource utilization information may further comprise anumerator and/or a denominator for the ratio of used grant freeresources, the collision ratio of grant free resources, the attemptcollision ratio of one or more wireless devices, and/or the like. In anexample, the grant free resource utilization information may comprise atleast one of: a number of wireless devices activated to use grant freeresources; an average number of wireless devices activated to use grantfree resources; and/or the like. In an example, the grant free resourceutilization information may comprise a time period to determine one ormore elements of the grant free resource utilization information.

The grant free resource utilization information may be for one or moregrant free resources associated with at least one of: a grant freeresource scheduling information (e.g. frequency, timing, periodicity,scheduling interval, and/or the like), a type of services (e.g. bearertype, slice type, and/or the like), a wireless device type (e.g.wireless device subscription type, a URLLC wireless device type, machinetype communication wireless device type, and/or the like), a numerologyconfiguration information (e.g. which TTI is utilized for the configuredone or more grant free resources), one or more wireless deviceidentifiers of one or more wireless devices (e.g. C-RNTI, SPSC-RNTI,IMSI, temporary wireless device identifier for a grant free resource,and/or the like), a grant free resource configuration index, one or morebeams to support the one or more grant free resources, and/or the like.

In an example, the distributed radio access network entity may transmit,to the central radio access network entity, a grant free resourceconfiguration shift indication indicating that the distributed radioaccess network entity shifts a grant free resource configuration (e.g.grant free resource scheduling configuration) for one or more wirelessdevice to another grant free resource configuration. The grant freeresource configuration shift indication may comprise one or more grantfree resource configuration index and/or one or more wireless deviceidentifiers of one or more wireless devices associated with the grantfree resource configuration shift indication.

In an example, the central radio access network entity may configure oneor more grant free resources of the serving cell of the distributedradio access network entity at least based on one or more elements ofthe grant free resource utilization information received via the firstmessage.

In an example, if the grant free resource utilization informationreceived via the first message indicates that a collision ratio of grantfree resources for a first service type in a first serving cell is 50%,the central radio access network entity may decide to increase an amountof grant free resources for the first service type in the first servingcell, may reschedule (increase) grant free resources for the firstservice type, and/or may transmit the rescheduled grant free resourceconfiguration information to the distributed radio access network entityand/or one or more associated wireless devices. In this case (i.e. acollision ratio of grant free resources for a first service type in afirst serving cell is 50%), the central radio access network entity maydecide to decrease a number of wireless devices allowed to utilize thegrant free resources, may reconfigure a list of wireless devices allowedto utilize the grant free resources, and/or may transmit the list to thedistributed radio access network entity.

In an example, the central radio access network entity may transmit, tothe distributed radio access network entity, a second message comprisinga third grant free resource configuration information associated withthe one or more grant free resources configured at least based on one ormore elements of the grant free resource utilization informationreceived via the first message. The third grant free resourceconfiguration information may comprise at least one of: a grant freeresource scheduling information (e.g. frequency, timing, periodicity,scheduling interval, and/or the like), a type of services (e.g. bearertype, slice type, and/or the like) allowed to utilize the determined oneor more grant free resources, a wireless device type (e.g. wirelessdevice subscription type, a URLLC wireless device type, machine typecommunication wireless device type, and/or the like) allowed to utilizethe determined one or more grant free resources, a numerologyconfiguration information (e.g. which TTI is utilized for the determinedone or more grant free resources), one or more wireless deviceidentifiers of one or more wireless devices allowed to utilize thedetermined one or more grant free resources (e.g. C-RNTI, SPSC-RNTI,IMSI, temporary wireless device identifier for a grant free resource,and/or the like), a grant free resource configuration index, and/or thelike.

In an example, the third grant free resource configuration informationof the second message may comprise a scheduling configurationinformation of an increased number of grant free resources if one ormore elements of the grant free resource utilization information of thefirst message indicates that grant free resources assigned in theserving cell are not enough to support a requirement of wirelessdevices.

In an example, the central radio access network entity may transmit, toone or more wireless devices, a third message comprising a fourth grantfree resource configuration information (e.g. one or more radio resourcecontrol parameters) associated with the one or more grant free resourcesconfigured at least based on one or more elements of the grant freeresource utilization information received via the first message. In anexample, in response to receiving the fourth grant free resourceconfiguration information, the distributed radio access network entitymay configure one or more radio configuration parameters at least basedon one or more elements of the fourth grant free resource configurationinformation, and/or receive one or more packets from one or morewireless devices via one or more of the one or more grant free resourcesconfigured at least based on one or more elements of the grant freeresource utilization information. In an example, the fourth grant freeresource configuration information of the third message may comprise ascheduling configuration information of a decreased number of grant freeresources if one or more elements of the grant free resource utilizationinformation of the first message indicates that grant free resourcesassigned in the serving cell are used less than the central radio accessnetwork entity expected.

In an example, the central radio access network entity may transmit, tothe distributed radio access network entity, at least one of: a firstwireless device identifier of a first wireless device allowed to utilizeone or more of the one or more grant free resources configured at leastbased on one or more elements of the grant free resource utilizationinformation; and/or a wireless device specific message associated withthe first wireless device. In an example, the wireless device specificmessage may comprise at least one of: one or more elements of the fourthgrant free resource configuration information; and/or a grant freeresource index of the one or more elements of the fourth grant freeresource configuration information. The distributed radio access networkentity may transmit, to the first wireless device at least based on oneor more elements of the second message, a grant free resource activationindication indicating when the first wireless device is allowed toutilize the one or more of the one or more grant free resourcesconfigured at least based on one or more elements of the grant freeresource utilization information. In an example, the central radioaccess network entity may transmit, to the first wireless device, agrant free resource activation indication indicating when the firstwireless device is allowed to utilize the one or more of the one or moregrant free resources configured at least based on one or more elementsof the grant free resource utilization information.

In an example, a central radio access network entity may receive, from adistributed radio access network entity, a first message comprising agrant free resource utilization information of a serving cell served bythe distributed radio access network entity. The central radio accessnetwork entity may configure one or more grant free resources of theserving cell at least based on the grant free resource utilizationinformation. The central radio access network entity may transmit, tothe distributed radio access network entity, a second message comprisinga first grant free resource configuration information associated withthe one or more grant free resources. In an example, the central radioaccess network entity may further transmit, to a wireless device, athird message comprising a second grant free resource configurationinformation at least based on the first grant free resourceconfiguration information.

In an example, the central radio access network entity may transmit, tothe distributed radio access network entity, at least one of: a firstwireless device identifier of a first wireless device allowed to utilizeone or more of the one or more grant free resources; and/or a wirelessdevice specific message associated with the first wireless deviceallowed to utilize one or more of the one or more grant free resources.The wireless device specific message may comprise at least one of thesecond grant free resource configuration information and/or a grant freeresource index of the second grant free resource configurationinformation. The distributed radio access network entity may transmit tothe first wireless device, a grant free resource activation indicationindicating when the first wireless device is allowed to utilize one ormore of the one or more grant free resources.

In an example, the first message may be transmitted at least based on afourth message transmitted by the central radio access network entity tothe distributed radio access network entity. The fourth message may beconfigured to request the grant free resource utilization information.The fourth message comprises at least one of: a triggering condition oftransmitting the grant free resource utilization information; and/or areporting periodicity of reporting the grant free resource utilizationinformation.

In an example, the grant free resource utilization information maycomprise at least one of: a ratio of used grant free resources; apercentage of used grant free resources; a collision ratio of grant freeresources (with a denominator: used GF resources and/or all GFresources); a collision ratio of access attempts of a wireless device togrant free resources; a number of access attempts of a wireless device;a grant free resource monitoring period information for one or more ofthe grant free resource utilization information; a number of wirelessdevices activated to utilize grant free resources (e.g. per beam and/orper cell); an average number of wireless devices activated to utilizegrant free resources; and/or the like. The grant free resourceconfiguration information may comprises at least one of a frequencyinformation, a time information, and/or an interval information of oneor more grant free resources.

Distributed Unit Status Information

In an example embodiment, a distributed radio access network entity (DU,distributed unit) may transmit, to a central radio access network entity(CU, central unit), a radio resource status information of a licensedassisted access (LAA) cell served by the distributed radio accessnetwork entity. The central radio access network entity may configureand/or reconfigure one or more configuration parameters for the licensedassisted access cell at least based on the radio resource statusinformation. The central radio access network entity may request, to thedistributed radio access network entity, a radio resource statusinformation report for a licensed assisted access cell with an eventbased condition for the report and/or a periodicity to report.

In an example, a distributed radio access network entity may beconnected to a central radio access network entity. The two entities maybe connected via an F1 interface. One or more licensed assisted access(LAA) cells of the distributed radio access network entity may utilizeone or more unlicensed spectrums (one or more unlicensed frequencybands). The one or more unlicensed spectrums may be shared with one ormore networks, e.g. WLAN, other LTE networks, and/or the like. In anexample, to share the one or more unlicensed spectrums with othernetworks, the distributed radio access network entity may use an LBT(Listen Before Talk) function, in which the distributed radio accessnetwork entity may detect energy level from other networks on itstransmission frequency before transmitting packets through thefrequency. In an example, if the energy level detected is higher than athreshold, the distributed radio access network entity may not transmitpackets via the frequency.

In an example, as shown in FIG. 23 and/or FIG. 24, the central radioaccess network entity may transmit, to the distributed radio accessnetwork entity, a fourth message configured to request a radio resourcestatus information of one or more licensed assisted access cells servedby the distributed radio access network entity. In an example, thefourth message may be transmitted via the F1 interface. The fourthmessage may be a resource status request message. The fourth message maycomprise at least one of: one or more cell identifiers (e.g. global cellidentifier, physical cell identifier, unique cell identifier at least atthe distributed radio access network entity, and/or the like) of one ormore licensed assisted access cells that the central radio accessnetwork entity requests a radio resource status information for, atriggering condition of transmitting a radio resource statusinformation; and/or a reporting periodicity of reporting a radioresource status information.

In an example, the triggering condition may comprise at least one of: amaximum LBT Failure Ratio threshold; a minimum LBT Failure Ratiothreshold; a maximum LBT Success Ratio threshold; a minimum LBT SuccessRatio threshold; a maximum PRB Tried threshold; a minimum PRB Triedthreshold; a maximum PRB Failed threshold; a minimum PRB Failedthreshold; a maximum PRB Used threshold; a minimum PRB Used threshold; amaximum PRB Usage threshold; a minimum PRB Usage threshold; a maximumContention Level threshold; a minimum Contention Level threshold; amaximum Average CW (contention window) threshold; a minimum Average CWthreshold; a maximum Current CW threshold; a minimum Current CWthreshold; an indication indicating that the distributed radio accessnetwork entity may report a radio resource status information if absenceof any other technology (network) is detected; and/or the like.

In an example, if one or more of measured results are same and/or largerthan one or more associated maximum thresholds of the triggeringcondition, the distributed radio access network entity may transmit aradio resource status information of one or more licensed assistedaccess cells to the central radio access network entity. In an example,if one or more of measured results are same and/or smaller than one ormore associated minimum thresholds of the triggering condition, thedistributed radio access network entity may transmit a radio resourcestatus information of one or more licensed assisted access cells to thecentral radio access network entity. The fourth message may furthercomprise a period to measure a radio resource status of one or morelicensed assisted access cells to determine whether one or more elementsof the triggering condition are satisfied.

In an example, the distributed radio access network entity may transmit,to the central radio access network entity, a first message comprising aradio resource status information of a licensed assisted access cell(LAA cell) served by the distributed radio access network entity. Thefirst message may be determined and/or transmitted at least based on oneor more elements of the fourth message. In an example, the first messagemay be transmitted via the F1 interface. The first message may be aresource status update message. In an example, one or more elements ofthe radio resource status information may be determined at least basedon the period to measure a radio resource status, the period receivedvia the fourth message.

In an example, as shown in FIG. 25 and/or FIG. 26, the radio resourcestatus information of the licensed assisted access cell may comprise LBTFailure Ratio, LBT Success Ratio, PRB Tried, PRB Failed, PRB Used, PRBUsage, Contention Level, Average CW, Current CW, and/orabsenceOfAnyOtherTechnology for the licensed assisted access cell (LAAcell). In an example, the absenceOfAnyOtherTechnology may indicateabsence or presence of any other network sharing a frequency band usedby the licensed assisted access cell of the distributed radio accessnetwork entity. In an example, the LBT Failure Ratio, the LBT SuccessRatio, the PRB Tried, the PRB Failed, the PRB Used, and/or the PRB Usagemay be determined in the time domain and/or in the time-frequencydomain. In an example, in case of determining only in time domain, ifone or more frequency domain resource blocks (PRBs) in a time slot areused for packet transmission, the time slot may be considered as used.In an example, if packet transmission starts or ends at the middle of aPRB (slot), the PRB may be considered as used. In an example, if packettransmission starts or ends at the middle of a PRB (slot), the PRB maybe considered as failed.

In an example, the Contention Level may comprise a parameter indicatinga level of contention on an unlicensed spectrum of the LAA cell (e.g.high contention, low contention; high contention, medium contention, lowcontention; or high contention, high medium contention, mediumcontention, low medium contention, low contention). For example, if theunlicensed spectrum is highly occupied by other networks (e.g. if afailure ratio in transmission attempts by the LAA cell is higher than athreshold, wherein the failure occurs because one or more other networksare transmitting through the unlicensed spectrum shared with the LAAcell), the Contention Level may be the high contention. For example, ifthe unlicensed spectrum is rarely occupied by other networks (e.g. ifthe failure ratio in transmission attempts by the LAA cell is lower thana threshold), the Contention Level may be the low contention.

In an example, the LBT Failure Ratio may comprise a ratio of a number ofPRBs that the LAA cell used for packet transmission or tried to use butfailed because of other networks' transmissions and a number of PRBsthat the LAA cell tried to use for packet transmission but failedbecause of other networks' transmissions for a measurement time periodduring which resource status measurements are performed. For example,

${{{LBT}\mspace{14mu} {Failure}\mspace{14mu} {{Ratio}(T)}} = {\frac{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {failed}\mspace{14mu} {in}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}{\begin{matrix}{{{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {used}\mspace{14mu} {for}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}} +}\mspace{11mu}} \\{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {failed}\mspace{14mu} {in}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}\end{matrix}}*100}},$

where T is the measurement time period. In an example, for uplinktransmission, the number of PRBs used for packet transmission or failedmay be equivalent to the number of PRBs allocated for uplinktransmission. In an example, for uplink transmission, a UE may reportinformation of PRBs failed to use because of other networks'transmission to its serving eNB. In an example, for uplink transmission,an eNB may consider PRBs that the eNB allocated to a UE for uplinktransmission but could not receive packets through as PRBs failed inpacket transmission. In an example, the LBT Failure Ratio may beprovided for downlink transmissions, for uplink transmission, and/or forall transmissions including both downlink and uplink transmissions.

In an example, the LBT Success Ratio may comprise a ratio of a number ofPRBs that the LAA cell used for packet transmission or tried to use butfailed because of other networks' transmissions and a number of PRBsthat the LAA cell used for packet transmission during the measurementtime period. For example,

${{{LBT}\mspace{14mu} {Success}\mspace{14mu} {{Ratio}(T)}} = {\frac{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {used}\mspace{14mu} {for}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}{\begin{matrix}{{{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {used}\mspace{14mu} {for}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}} +}\mspace{11mu}} \\{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {failed}\mspace{14mu} {in}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}\end{matrix}}*100}},$

where T is the measurement time period. In an example, for uplinktransmission, the number of PRBs used for packet transmission or failedmay be equivalent to the number of PRBs allocated for uplinktransmission. In an example, for uplink transmission, a UE may reportinformation of PRBs used for packet transmission to its serving eNB. Inan example, for uplink transmission, an eNB may consider PRBs that theeNB received packets through as PRBs used for packet transmission. In anexample, the LBT Failure Ratio may be provided for downlinktransmissions, for uplink transmission, and/or for all transmissionsincluding both downlink and uplink transmissions.

In an example, the PRB Tried may comprise a ratio of a number of allPRBs available and a number of PRBs that the LAA cell used for packettransmission or tried to use but failed because of other networks'transmissions during the measurement time period. For example,

${{{PRB}\mspace{14mu} {Tried}(T)} = {\frac{\begin{matrix}{{{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {used}\mspace{14mu} {for}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}} +}\mspace{11mu}} \\{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {failed}\mspace{14mu} {in}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}\end{matrix}}{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {{available}(T)}}*100}},$

where T is the measurement time period. In an example, for uplinktransmission, the number of PRBs used for packet transmission or failedmay be equivalent to the number of PRBs allocated for uplinktransmission. In an example, the PRB Tried may be provided for downlinktransmissions, for uplink transmission, and/or for all transmissionsincluding both downlink and uplink transmissions.

In an example, the PRB Failed may comprise a ratio of a number of allPRBs available and a number of PRBs that the LAA cell tried to use forpacket transmission but failed because of other networks' transmissionsduring the measurement time period. For example,

${{{PRB}\mspace{14mu} {Failed}(T)} = {\frac{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {failed}\mspace{14mu} {in}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {{available}(T)}}*100}},$

where T is the measurement time period. In an example, for uplinktransmission, a UE may report information of PRBs failed to use becauseof other networks' transmission to its serving eNB. In an example, foruplink transmission, an eNB may consider PRBs that the eNB allocated toa UE for uplink transmission but could not receive packets through asPRBs failed in packet transmission. In an example, the PRB Failed may beprovided for downlink transmissions, for uplink transmission, and/or forall transmissions including both downlink and uplink transmissions.

In an example, the PRB Used may comprise a ratio of a number of all PRBsavailable and a number of PRBs that the LAA cell used for packettransmission during the measurement time period. For example,

${{{PRB}\mspace{14mu} {Used}(T)} = {\frac{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {used}\mspace{14mu} {for}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {{available}(T)}}*100}},$

where T is the measurement time period.

In an example, for uplink transmission, a UE may report information ofPRBs used for packet transmission to its serving eNB. In an example, foruplink transmission, an eNB may consider PRBs that the eNB receivedpackets through as PRBs used for packet transmission. In an example, thePRB Used may be provided for downlink transmissions, for uplinktransmission, and/or for all transmissions including both downlink anduplink transmissions.

In an example, the PRB Usage may comprise Downlink PRB Usage and/orUplink PRB Usage. In an example, the Downlink PRB Usage may comprise aratio of a number of all PRBs available and a number of PRBs that theLAA cell used for downlink packet transmission during the measurementtime period. For example,

${{{Downlink}\mspace{14mu} {PRB}\mspace{14mu} {{Usage}(T)}} = {\frac{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {used}\mspace{14mu} {for}\mspace{14mu} {downlink}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {{available}(T)}}*100}},$

where T is the measurement time period. In an example, the Uplink PRBUsage may comprise a ratio of the number of all PRBs available and thenumber of PRBs that the LAA cell used for uplink packet transmission ortried to use for uplink packet transmission but failed because of othernetworks' transmissions during the measurement time period. For example,

${{{Uplink}\mspace{14mu} {PRB}\mspace{14mu} {{Usage}(T)}} = {\frac{\begin{matrix}{{{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {used}\mspace{14mu} {for}\mspace{14mu} {uplink}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}} +}\mspace{11mu}} \\{{number}\mspace{20mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {failed}\mspace{14mu} {in}\mspace{14mu} {uplink}\mspace{14mu} {packet}\mspace{14mu} {{transmission}(T)}}\end{matrix}}{{number}\mspace{14mu} {of}\mspace{14mu} {PRBs}\mspace{14mu} {{available}(T)}}*100}},$

where T is the measurement time period. In an example, for the UplinkPRB Usage, the number of PRBs used for uplink packet transmission orfailed may be equivalent to the number of PRBs allocated for uplinktransmission.

In an example, the Average CW may comprise average contention windowsizes of each channel access priority class (e.g. CWp=1, CWp=2, CWp=3,and/or CWp=4) for a measurement time period during which statusmeasurements are performed and/or total average contention window sizeof all channel access priority classes for the measurement time period.In an example, the average contention window size may be calculated byaveraging (e.g. combining) all contention window sizes used in everychannel access procedure for transmission during the measurement timeperiod for each channel access priority class. For example,

${{average}\mspace{14mu} {contention}\mspace{14mu} {window}\mspace{14mu} {{size}_{p}(T)}} = {\frac{{sum}\mspace{14mu} {of}\mspace{14mu} {contention}\mspace{14mu} {window}\mspace{14mu} {sizes}\mspace{14mu} {for}\mspace{14mu} {each}\mspace{14mu} {{transmission}_{p}(T)}}{{number}\mspace{14mu} {of}\mspace{14mu} {all}\mspace{14mu} {{transmissions}_{p}(T)}}.}$

where T is the measurement time period, and p is the channel accesspriority class, e.g. p=1, 2, 3, or 4. In an example, the total averagecontention window size may be calculated by averaging all contentionwindow sizes used in every channel access procedure for transmission forall channel access priority class during the measurement time period.For example,

${{total}\mspace{14mu} {average}\mspace{14mu} {contention}\mspace{14mu} {window}\mspace{14mu} {size}} = {\frac{\begin{matrix}{\sum_{p = 1}^{4}{{sum}\mspace{14mu} {of}\mspace{14mu} {contention}\mspace{14mu} {window}}} \\{{sizes}\mspace{14mu} {for}\mspace{14mu} {each}\mspace{14mu} {{transmission}_{p}(T)}}\end{matrix}\mspace{14mu}}{\sum_{p = 1}^{4}{{number}\mspace{14mu} {of}\mspace{14mu} {all}\mspace{14mu} {{transmissions}_{p}(T)}}}.}$

In an example, the Average CW may be provided for downlinktransmissions, for uplink transmission, and/or for all transmissionsincluding both downlink and uplink transmissions. In an example, uplinktransmissions using the type 2 UL channel access procedure are excludedin calculation of the Average CW.

In an example, the Current CW may comprise current contention windowsizes for each channel access priority class (e.g. CWp=1, CWp=2, CWp=3,and/or CWp=4) and/or total current contention window size of all channelaccess priority classes. In an example, the current contention windowsize for each channel access priority class may be a contention windowsize that the LAA cell is currently using for packet transmission of thechannel access priority class. In an example, the total currentcontention window size may be calculated by averaging the currentcontention window sizes for each channel access priority class. Forexample,

${{{total}\mspace{14mu} {current}\mspace{14mu} {contention}\mspace{14mu} {window}\mspace{14mu} {size}} = \frac{\sum_{p = 1}^{4}{{current}\mspace{14mu} {contention}\mspace{14mu} {window}\mspace{14mu} {size}_{p}}}{{number}\mspace{14mu} {of}\mspace{14mu} {channel}\mspace{14mu} {access}\mspace{14mu} {priority}\mspace{14mu} {classes}}},$

where the number of channel access priority classes may be 4. In anexample, the Current CW may be provided for downlink transmissions, foruplink transmission, and/or for all transmissions including bothdownlink and uplink transmissions. In an example, uplink transmissionsusing the type 2 UL channel access procedure are excluded in calculationof the Current CW.

In an example, the central radio access network entity may configure oneor more network configuration parameters of the LAA cell of thedistributed radio access network entity at least based on one or moreelements of the radio resource status information of the LAA cellreceived via the first message from the distributed radio access networkentity.

In an example, if an LBT Failure Ratio for the LAA cell in the firstmessage is 90%, the central radio access network entity may consider theunlicensed frequency of the LAA cell is highly congested. In this case,the central radio access network may redirect one or more wirelessdevices served via LAA cell to another cell (e.g. another LAA cell usinganother unlicensed frequency, and/or a cell using a licensed frequency).The central radio access network may initiate a handover of one or moreof the one or more wireless device towards another cell, and/or addsecondary cells for one or more of the one or more wireless devices.

In an example, if a PRB Usage for the LAA cell in the first message is10%, the central radio access network entity may consider that theunlicensed frequency of the LAA cell is not congested and/or has anenough capacity to support more packet transmissions. In this case, thecentral radio access network may allow more wireless devices to utilizethe LAA cell. The central radio access network may transmit, to aneighboring base station, a resource status information of the LAA cell,and/or the neighboring base station may initiate a handover and/or asecondary base station addition towards the LAA cell. The central radioaccess network may also add the LAA cell as a secondary cell for otherwireless devices.

In an example, the central radio access network entity may transmit, tothe distributed radio access network entity, a second message comprisingone or more of the one or more network configuration parameters. Thedistributed radio access network entity may configure one or morenetwork configuration parameters at least based on one or more elementsof the second message. In an example, the central radio access networkentity may transmit, to one or more wireless devices, a third messagecomprising one or more radio resource control configuration parametersat least based on the one or more network configuration parameters. Theone or more wireless device may transmit and/or receive one or morepackets via the LAA cell at least based on one or more elements of thethird message. In an example, the one or more network configurationparameters of the second message may be to add or remove the LAA cell asa secondary cell for one or more wireless devices. In an example, theone or more radio resource radio resource control configurationparameters may be a command for a wireless device to add or remove theLAA cell as a secondary cell.

In an example, the central radio access network entity may transmit, toa first radio access network entity (e.g. neighboring base station), afifth message at least based on one or more elements of the firstmessage and/or the radio resource status information for the LAA cellreceived via the first message. The fifth message may be configured toindicate at least one of: a load status of the licensed assisted access(LAA) cell with one or more elements of the radio resource statusinformation (e.g. load information message and/or resource status updatemessage); a handover request towards a cell of the first radio accessnetwork entity (e.g. handover request message); a handover requestacknowledge configured to accept a handover request received by thecentral radio access network entity from the first radio access networkentity (e.g. handover request acknowledge message); a handoverpreparation failure configured to reject a handover request received bythe central radio access network entity from the first radio accessnetwork entity (e.g. handover preparation failure message); and/or thelike.

In an example, the fifth message may be configured to indicate at leastone of: a multi (and/or dual) connectivity initiation request for one ormore cells of the first radio access network entity (e.g. SgNB additionrequest message and/or SeNB addition request message); a multi (and/ordual) connectivity initiation request acknowledge configured to accept amulti connectivity initiation request received by the central radioaccess network entity from the first radio access network entity (e.g.SgNB addition request acknowledge message and/or SeNB addition requestacknowledge message); a multi (and/or dual) connectivity initiationrequest reject configured to reject a multi connectivity initiationrequest received by the central radio access network entity from thefirst radio access network entity (e.g. SgNB addition request rejectmessage and/or SeNB addition request reject message); and/or the like.

In an example, the fifth message may be configured to indicate at leastone of: a multi (and/or dual) connectivity modification request for oneor more cells of the first radio access network entity (e.g. SgNBmodification request message and/or SeNB modification request message);a multi (and/or dual) connectivity modification request acknowledgeconfigured to accept a multi connectivity modification request receivedby the central radio access network entity from the first radio accessnetwork entity (e.g. SgNB modification request acknowledge messageand/or SeNB modification request acknowledge message); a multi (and/ordual) connectivity modification request reject configured to reject amulti connectivity modification request received by the central radioaccess network entity from the first radio access network entity (e.g.SgNB modification request reject message and/or SeNB modificationrequest reject message); and/or the like.

In an example, the fifth message may be configured to indicate at leastone of: a multi (and/or dual) connectivity modification required for oneor more cells of the distributed radio access network entity (e.g. SgNBmodification required message and/or SeNB modification requiredmessage); a multi (and/or dual) connectivity modification confirmationconfigured to accept a multi connectivity modification requirementreceived by the central radio access network entity from the first radioaccess network entity (e.g. SgNB modification confirm message and/orSeNB modification confirm message); a multi (and/or dual) connectivitymodification refusal configured to reject a multi connectivitymodification requirement received by the central radio access networkentity from the first radio access network entity (e.g. SgNBmodification refuse message and/or SeNB modification refuse message);and/or the like.

In an example, the fifth message may be configured to indicate at leastone of: a multi (and/or dual) connectivity release request for one ormore cells of the first radio access network entity (e.g. SgNB releaserequest message and/or SeNB release request message); a multi (and/ordual) connectivity release required for one or more cells of thedistributed radio access network entity (e.g. SgNB release requiredmessage and/or SeNB release required message); a multi (and/or dual)connectivity release confirmation configured to accept a multiconnectivity release requirement received by the central radio accessnetwork entity from the first radio access network entity (e.g. SgNBrelease confirm message and/or SeNB release confirm message); and/or thelike.

In an example, a central radio access network entity may receive, from adistributed radio access network entity, a first message comprising aradio resource status information of a licensed assisted access cellserved by the distributed radio access network entity. The radioresource status information may comprise at least one of an LBT FailureRatio, an LBT Success Ratio, a PRB Tried, a PRB Failed, a PRB Used, aPRB Usage, a Contention Level, an Average CW, a Current CW, and/or anabsenceOfAnyOtherTechnology. The central radio access network entity mayconfigure one or more network configuration parameters at least based onthe radio resource status information. The central radio access networkentity may transmit, to the distributed radio access network entity, asecond message comprising one or more of the one or more networkconfiguration parameters.

In an example, the central radio access network entity may transmit, toa wireless device, a third message comprising one or more radio resourcecontrol configuration parameters at least based on the one or morenetwork configuration parameters. The first message may be transmittedat least based on a fourth message transmitted by the central radioaccess network entity to the distributed radio access network entity.The fourth message may be configured to request the radio resourcestatus information of the licensed assisted access cell. The fourthmessage may comprise at least one of: a triggering condition oftransmitting the radio resource status information; and/or a periodicityof transmitting the radio resource status information.

In an example, the central radio access network entity may transmit, toa first radio access network entity, a fifth message at least based onone or more elements of the first message. The fifth message may beconfigured to indicate at least one of: a load status of the licensedassisted access cell with one or more elements of the radio resourcestatus information; a handover request; a handover request acknowledgeconfigured to accept a handover request received by the central radioaccess network entity from the first radio access network entity; ahandover preparation failure configured to reject a handover requestreceived by the central radio access network entity from the first radioaccess network entity; a multi connectivity initiation request; a multiconnectivity initiation request acknowledge configured to accept a multiconnectivity initiation request received by the central radio accessnetwork entity from the first radio access network entity; a multiconnectivity initiation request reject configured to reject a multiconnectivity initiation request received by the central radio accessnetwork entity from the first radio access network entity; a multiconnectivity modification request; a multi connectivity modificationrequest acknowledge configured to accept a multi connectivitymodification request received by the central radio access network entityfrom the first radio access network entity; a multi connectivitymodification request reject configured to reject a multi connectivitymodification request received by the central radio access network entityfrom the first radio access network entity; and/or the like.

According to various embodiments, a device such as, for example, awireless device, off-network wireless device, a base station, and/or thelike, may comprise one or more processors and memory. The memory maystore instructions that, when executed by the one or more processors,cause the device to perform a series of actions. Embodiments of exampleactions are illustrated in the accompanying figures and specification.Features from various embodiments may be combined to create yet furtherembodiments.

FIG. 41 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4110, a base station distributed unit mayreceive, from a base station central unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit. At 4120, the base stationdistributed unit may transmit, to the wireless device, the PDCP packetsvia the radio bearer. At 4130, the base station distributed unit mayinitiate a bearer release procedure. The bearer release procedure maycomprise transmitting, to the base station central unit, a firstmessage. The first message may comprise a first data radio beareridentifier of the radio bearer to be released. At 4140, the base stationdistributed unit may receive, from the base station central unit, asecond message confirming release of the radio bearer by the basestation central unit. At 4150, the base station distributed unit mayreceive, from the base station central unit, a radio resource controlmessage for the wireless device. The radio resource control message maycomprise the first data radio bearer identifier of the radio bearer tobe released by the wireless device. At 4160, the base stationdistributed unit may transmit, to the wireless device, the radioresource control message.

According to an embodiment, the base station distributed unit mayrelease the radio bearer as part of the bearer release procedure.According to an embodiment, the base station distributed unit mayrelease the radio bearer based on the first message.

According to an embodiment, the base station distributed unit maytransmit the first message based on a load status of the base stationdistributed unit. According to an embodiment, the base stationdistributed unit may transmit the first message based on a radio loadstatus of one or more cells of the base station distributed unit.According to an embodiment, the base station distributed unit maytransmit the first message based on an uplink or downlink buffer stateinformation of the wireless device. According to an embodiment, the basestation distributed unit may transmit the first message based on a timealignment timer expiration. According to an embodiment, the base stationdistributed unit may transmit the first message based on a channel stateinformation received from the wireless device. According to anembodiment, the base station distributed unit may transmit the firstmessage based on an uplink channel measurement by the base stationdistributed unit. According to an embodiment, the base stationdistributed unit may transmit the first message based on a radio linkinterference associated with the wireless device. According to anembodiment, the base station distributed unit may transmit the firstmessage based on a radio link interference associated with one or morecells of the base station distributed unit. According to an embodiment,the base station distributed unit may transmit the first message basedon one or more radio link configuration changes.

According to an embodiment, the first message may comprise a first dataradio bearer identifier of a second data radio bearer required to bereleased. According to an embodiment, the first message may comprise asecond data radio bearer identifier of a second data radio bearerrequired to be modified. According to an embodiment, the first messagemay comprise one or more radio configuration parameters to be changed.According to an embodiment, the first message may comprise one or morebeam information of one or more beams recovered by the wireless device.According to an embodiment, the first message may comprise one or morebeam information of one or more beams serving the wireless device.According to an embodiment, the first message may comprise one or morebeam information of one or more beams released by the wireless device.According to an embodiment, the first message may comprise aninformation element indicating that the wireless device changed one ormore serving beams.

According to an embodiment, the radio resource control message mayfurther comprise one or more radio resource control parametersdetermined based on the first message. The one or more radio resourcecontrol parameters may comprise a second data radio bearer identifier ofa second data radio bearer required to be modified. The one or moreradio resource control parameters may comprise one or more radio linkconfiguration parameters to be changed.

According to an embodiment, the base station distributed unit may decodethe radio resource control message. According to an embodiment, the basestation distributed unit may determine one or more radio linkconfigurations based on the radio resource control message.

FIG. 42 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4210, a base station central unit maytransmit, to a base station distributed unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit. At 4220, the base stationcentral unit may receive, from the base station distributed unit, afirst message comprising a first data radio bearer identifier of theradio bearer to be released. The first message may initiate a bearerrelease procedure. At 4230, the base station central unit may transmit,to the base station distributed unit, a second message confirmingrelease of the radio bearer. At 4240, the base station central unit maytransmit, to the base station distributed unit, a radio resource controlmessage for the wireless device. The radio resource control message maycomprise the first data radio bearer identifier of the radio bearer tobe released by the wireless device.

According to an embodiment, the base station distributed unit mayrelease the radio bearer as part of the bearer release procedure.According to an embodiment, the base station central unit may releasethe radio bearer based on the first message.

According to an embodiment, the base station distributed unit maytransmit the first message based on a load status of the base stationdistributed unit. According to an embodiment, the base stationdistributed unit may transmit the first message based on a radio loadstatus of one or more cells of the base station distributed unit.According to an embodiment, the base station distributed unit maytransmit the first message based on an uplink or downlink buffer stateinformation of the wireless device. According to an embodiment, the basestation distributed unit may transmit the first message based on a timealignment timer expiration. According to an embodiment, the base stationdistributed unit may transmit the first message based on a channel stateinformation received from the wireless device. According to anembodiment, the base station distributed unit may transmit the firstmessage based on an uplink channel measurement by the base stationdistributed unit. According to an embodiment, the base stationdistributed unit may transmit the first message based on a radio linkinterference associated with the wireless device. According to anembodiment, the base station distributed unit may transmit the firstmessage based on. According to an embodiment, the base stationdistributed unit may transmit the first message based on a radio linkinterference associated with one or more cells of the base stationdistributed unit. According to an embodiment, the base stationdistributed unit may transmit the first message based on one or moreradio link configuration changes.

According to an embodiment, the first message may comprise a first dataradio bearer identifier of a second data radio bearer required to bereleased. According to an embodiment, the first message may comprise asecond data radio bearer identifier of a second data radio bearerrequired to be modified. According to an embodiment, the first messagemay comprise one or more radio configuration parameters to be changed.According to an embodiment, the first message may comprise one or morebeam information of one or more beams recovered by the wireless device.According to an embodiment, the first message may comprise one or morebeam information of one or more beams serving the wireless device.According to an embodiment, the first message may comprise one or morebeam information of one or more beams released by the wireless device.According to an embodiment, the first message may comprise aninformation element indicating that the wireless device changed one ormore serving beams.

According to an embodiment, the radio resource control message mayfurther comprise one or more radio resource control parametersdetermined based on the first message. According to an embodiment, theone or more radio resource control parameters may comprise a second dataradio bearer identifier of a second data radio bearer required to bemodified. According to an embodiment, the one or more radio resourcecontrol parameters may comprise one or more radio link configurationparameters to be changed.

FIG. 43 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4310, a base station distributed unit mayreceive, from a base station central unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit. At 4320, the base stationdistributed unit may transmit, to the wireless device, the PDCP packetsvia the radio bearer. At 4330, the base station distributed unit mayinitiate a bearer release procedure. The bearer release procedure maycomprise transmitting, to the base station central unit, a firstmessage. The first message may comprise a first data radio beareridentifier of the radio bearer to be modified. At 4340, the base stationdistributed unit may receive, from the base station central unit, asecond message confirming modification of the radio bearer by the basestation central unit. At 4350, the base station distributed unit mayreceive, from the base station central unit, a radio resource controlmessage for the wireless device. The radio resource control message maycomprise the first data radio bearer identifier of the radio bearer tobe modified by the wireless device. At 4360, the base stationdistributed unit may transmit, to the wireless device, the radioresource control message.

According to an embodiment, the second message may comprise a firstinformation element. According to an embodiment, the first informationelement may indicate accepting one or more elements of the firstmessage. According to an embodiment, the first information element mayindicate rejecting one or more elements of the first message. Accordingto an embodiment, the first information element may indicate confirmingone or more elements of the first message.

FIG. 44 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4410, a base station distributed unit maytransmit, to a base station central unit, a first message indicating amodification request of a wireless device context of a wireless device.The wireless device context may comprise a first data radio beareridentifier of a first data radio bearer required to be released. At4420, the base station distributed unit may receive, from the basestation central unit and in response to the first message, a secondmessage. The second message may indicate confirmation of updating thewireless device context based on the first message. At 4430, the basestation distributed unit may receive, from the base station centralunit, a radio resource control message for the wireless device. Theradio resource control message may comprise the first data radio beareridentifier of the first data radio bearer required to be released. At4440, the base station distributed unit may transmit, to the wirelessdevice, the radio resource control message.

FIG. 45 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4510, a base station central unit maytransmit, to a base station distributed unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit. The base station distributedunit may transmit the PDCP packets to the wireless device via the radiobearer. At 4520, the base station central unit may receive, from thebase station distributed unit, a first message. The first message maycomprise a first data radio bearer identifier of the radio bearer to bereleased. The first message may initiate a bearer release procedure. At4530, the base station central unit transmit, to the base stationdistributed unit, a second message confirming release of the radiobearer. At 4540, the base station central unit may transmit, to the basestation distributed unit, a radio resource control message for thewireless device. The radio resource control message may comprise thefirst data radio bearer identifier of the radio bearer to be released bythe wireless device. The base station distributed unit may transmit theradio resource control message to the wireless device.

FIG. 46 is an example flow diagram as per as aspect of an embodiment ofthe present disclosure. At 4610, a base station distributed unit mayreceive, from a base station central unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit. At 4620, the base stationdistributed unit may transmit, to the wireless device, the PDCP packetsvia a radio link. At 4630, the base station distributed unit may detecta radio link outage of the radio link. At 4640, the base stationdistributed unit may transmit, to the base station central unit, a firstmessage. The first message may comprise one or more parameters. The oneor more parameters may comprise a first information element indicatingthe radio link outage. The one or more parameters may comprise a cellidentifier of a first cell associated with the radio link outage. At4650, the base station distributed unit may receive, from the basestation central unit and in response to the one or more parameters, asecond message indicating a release of a first wireless device contextof the radio bearer. At 4660, the base station distributed unit mayrelease the first wireless device context in response to the secondmessage.

According to an embodiment, the one or more parameters may furthercomprise a second information element indicating that a number ofdownlink packet retransmissions reaches a threshold number of downlinkpacket retransmissions. According to an embodiment, the one or moreparameters may further comprise a third information element indicatingat least one failure to receive a channel status information report fromthe wireless device. According to an embodiment, the one or moreparameters may further comprise a fourth information element indicatingexpiration of a time duration without receiving at least one transportblock from the wireless device. According to an embodiment, the one ormore parameters may further comprise a fifth information elementindicating at least one failure to receive a precoding matrix indicatorfrom the wireless device. According to an embodiment, the one or moreparameters may further comprise a sixth information element indicatingat least on failure to receive a rank indicator from the wirelessdevice. According to an embodiment, the one or more parameters mayfurther comprise a seventh information element indicating a connectionloss of the wireless device.

According to an embodiment, the base station central unit may determinea radio link failure of the wireless device based on the one or moreparameters of the first message. According to an embodiment, the basestation central unit may transmit, to a core network entity, a thirdmessage indicating a release request for a second wireless devicecontext of the wireless device. The second wireless device context maycomprise an interface connection between the base station central unitand the core network entity for the wireless device.

According to an embodiment, the first wireless device context maycomprise a data radio bearer. According to an embodiment, the firstwireless device context may comprise a logical channel. According to anembodiment, the first wireless device context may comprise a securityconfiguration parameter. According to an embodiment, the first wirelessdevice context may comprise an information parameter associated with thewireless device.

According to an embodiment, the second message may comprise a wirelessdevice identifier of the wireless device. According to an embodiment,the second message may comprise a first information element indicatingthat a cause of the release of the first wireless device context is aradio link failure of the wireless device.

According to an embodiment, the base station distributed unit maytransmit, to the base station central unit, a third message indicatingcompletion of the release of the first wireless device context.

FIG. 47 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4710, a base station central unit maytransmit, to a base station distributed unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit. The base station distributedunit may transmit the PDCP packets to the wireless device via a radiolink. At 4720, the base station central unit may receive, from the basestation distributed unit, a first message. The first message maycomprise one or more parameters. The one or more parameters may comprisea first information element indicating a radio link outage of the radiolink. The one or more parameters may comprise a cell identifier of afirst cell associated with the radio link outage. At 4730, the basestation central unit may transmit, to the base station distributed unitand in response to the one or more parameters, a second messageindicating a release of a first wireless device context of the radiobearer of the wireless device.

According to an embodiment, the base station distributed unit mayrelease the first wireless device context in response to the secondmessage.

According to an embodiment, the one or more parameters may furthercomprise a second information element indicating that a number ofdownlink packet retransmissions reaches a threshold number of downlinkpacket retransmissions. According to an embodiment, the one or moreparameters may further comprise a third information element indicatingat least one failure to receive a channel status information report fromthe wireless device. According to an embodiment, the one or moreparameters may further comprise a fourth information element indicatingexpiration of a time duration without receiving at least one transportblock from the wireless device. According to an embodiment, the one ormore parameters may further comprise a fifth information elementindicating at least one failure to receive a precoding matrix indicatorfrom the wireless device. According to an embodiment, the one or moreparameters may further comprise a sixth information element indicatingat least on failure to receive a rank indicator from the wirelessdevice. According to an embodiment, the one or more parameters mayfurther comprise a seventh information element indicating a connectionloss of the wireless device.

According to an embodiment, the base station central unit may determinea radio link failure of the wireless device based on the one or moreparameters of the first message.

According to an embodiment, the base station central unit may transmit,to a core network entity, a third message indicating a release requestfor a second wireless device context of the wireless device. The secondwireless device context may comprise an interface connection between thebase station central unit and the core network entity for the wirelessdevice.

According to an embodiment, the first wireless device context maycomprise a data radio bearer. According to an embodiment, the firstwireless device context may comprise a logical channel. According to anembodiment, the first wireless device context may comprise a securityconfiguration parameter. According to an embodiment, the first wirelessdevice context may comprise an information parameter associated with thewireless device.

FIG. 48 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4810, a base station distributed unit mayreceive, from a base station central unit, a wireless device contextsetup request for a wireless device. At 4820, the base stationdistributed unit may configure a first bearer of the wireless device inresponse to the wireless device context setup request. The base stationdistributed unit may provide a radio link control layer function for thefirst bearer. The base station central unit may provide a packet dataconvergence protocol layer function for the first bearer. At 4830, thebase station distributed unit may detect a radio link outage of a radiolink of the wireless device. At 4840, the base station distributed unitmay transmit, to the base station central unit, a first messagecomprising one or more parameters indicating the radio link outage. At4850, the base station distributed unit may receive, from the basestation central unit, a second message indicating a release of a firstwireless device context of the wireless device based on the one or moreparameters. The first wireless device context may comprise the firstbearer. At 4860, the base station distributed unit may release the firstwireless device context in response to the second message.

FIG. 49 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 4910, a base station distributed unit maydetect a radio link outage of a radio link of a wireless device. At4920, the base station distributed unit may transmit, to a base stationcentral unit, a first message comprising one or more parametersindicating the radio link outage. At 4930, the base station distributedunit may receive, from the base station central unit, a second messageindicating a release of a first wireless device context of the wirelessdevice based on the first message. At 4940, the base station distributedunit may release the first wireless device context in response to thesecond message.

FIG. 50 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 5010, a base station distributed unit mayreceive, from a base station central unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit. At 5020, the base stationdistributed unit may transmit, to the wireless device, the PDCP packetsvia a radio link. At 5030, the base station distributed unit may detecta radio link outage of the radio link. At 5040, the base stationdistributed unit may transmit, to the base station central unit, a firstmessage comprising one or more parameters indicating the radio linkoutage. At 5050, the base station distributed unit may receive, from thebase station central unit and in response to the one or more parameters,a second message indicating a release of a first wireless device contextof the wireless device. The first wireless device context may compriseone or more parameters of the radio bearer. At 5060, the base stationdistributed unit may release the first wireless device context inresponse to the second message.

FIG. 51 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 5110, a base station central unit maytransmit, to a first wireless device and via a base station distributedunit, a first message comprising first resource configuration parametersof periodic resources. The first resource configuration parameters maycomprise a periodicity of the periodic resources. The first resourceconfiguration parameters may comprise a first demodulation referencesignal. At 5120, the base station central unit may receive, from thebase station distributed unit, a second message comprising utilizationinformation of the periodic resources. At 5130, the base station centralunit may transmit, to a second wireless device and via the base stationdistributed unit, a third message based on the utilization information.The third message may comprise second resource configuration parametersof the periodic resources. The second resource configuration parametersmay comprise the periodicity of the periodic resources. The secondresource configuration parameters may comprise a second demodulationreference signal.

According to an embodiment, the utilization information may comprise avalue indicating utilized resources of the periodic resources. Accordingto an embodiment, the value may be a ratio of the utilized resources ofthe periodic resources to a total of the periodic resources. Accordingto an embodiment, the first resource configuration parameters mayfurther comprise a periodic resource index of the periodic resources.According to an embodiment, the periodic resources may be associatedwith a first cell.

According to an embodiment, the base station central unit may transmit,to the base station distributed unit, a fourth message comprising afirst configuration parameter indicating the first wireless deviceemploys the periodic resources. According to an embodiment, the basestation central unit may transmit, to the base station distributed unit,a fifth message comprising a second configuration parameter indicatingthe second wireless device employs the periodic resources.

According to an embodiment, the base station central unit may determinethat the second wireless device employs the periodic resources based onthe utilization information.

According to an embodiment, the base station distributed unit maytransmit to the second wireless device, a periodic resource activationcontrol information indicating when the second wireless device isallowed to employ the periodic resources.

According to an embodiment, the utilization information may indicate aratio of used periodic resources. According to an embodiment, theutilization information may indicate a percentage of used periodicresources. According to an embodiment, the utilization information mayindicate a collision ratio of the periodic resources. According to anembodiment, the utilization information may indicate a time periodconsidered for the utilization information. According to an embodiment,the utilization information may indicate a number of wireless devicesactivated to utilize the periodic resources.

According to an embodiment, the first resource configuration parametersand the second resource configuration parameters may further comprise asize of the periodic resources. According to an embodiment, the firstresource configuration parameters and the second resource configurationparameters may further comprise a frequency offset of the periodicresource.

According to an embodiment, the base station central unit may send, tothe base station distributed unit, a fourth message indicating a requestfor the utilization information of the periodic resources.

According to an embodiment, the fourth message may comprise a triggeringcondition for transmitting the utilization information. According to anembodiment, the fourth message may comprise a periodicity of reportingthe utilization information.

FIG. 52 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 5210, a base station central unit maytransmit, to a first wireless device, a first message comprisingresource configuration parameters of periodic resources of a first cell.At 5220, the base station central unit may transmit, to a base stationdistributed unit, a second message indicating a request for utilizationinformation of the periodic resources. At 5230, the base station centralunit may receive, from the base station distributed unit, a thirdmessage comprising the utilization information of the periodicresources. At 5240, the base station central unit may transmit, to thefirst wireless device and via the base station distributed unit, afourth message based on the utilization information. The fourth messagemay comprise resource configuration parameters of the periodicresources.

According to an embodiment, the utilization information may comprise afirst information element indicating a ratio of utilized resources ofthe periodic resources to a total of the periodic resources.

FIG. 53 is an example flow diagram as per an aspect of an embodiment ofthe present disclosure. At 5310, a base station central unit maytransmit, to a first wireless device and via a base station distributedunit, a first message comprising cell configuration parameters of alicensed assisted access cell. The cell configuration parameters maycomprise a cell identifier of the licensed assisted access cell. Thecell configuration parameters may comprise a listen-before-talkconfiguration parameter. At 5320, the base station central unit mayreceive, from the base station distributed unit, a second messagecomprising resource status information of the licensed assisted accesscell. The resource status information may comprise a value indicatinglisten-before-talk failure information of the licensed assisted accesscell. At 5330, the base station central unit may transmit, to a secondwireless device and via the base station distributed unit, a thirdmessage based on the resource status information. The third message maycomprise the cell configuration parameters of the licensed assistedaccess cell.

According to an embodiment, the resource status information may indicatea listen-before-talk failure ratio. According to an embodiment, theresource status information may indicate a listen-before-talk successratio. According to an embodiment, the resource status information mayindicate a first information of physical resource block tried to beemployed. According to an embodiment, the resource status informationmay indicate a second information of physical resource blocks failed tobe employed. According to an embodiment, the resource status informationmay indicate a third information of physical resource blocks employed.According to an embodiment, the resource status information may indicatea contention level. According to an embodiment, the resource statusinformation may indicate an average contention window size. According toan embodiment, the resource status information may indicate a currentcontention window size. According to an embodiment, the resource statusinformation may indicate an information element indicating absence ofother technology.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, wireless device or network nodeconfigurations, traffic load, initial system set up, packet sizes,traffic characteristics, a combination of the above, and/or the like.When the one or more criteria are met, various example embodiments maybe applied. Therefore, it may be possible to implement exampleembodiments that selectively implement disclosed protocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices and/or base stations may support multiple technologies, and/ormultiple releases of the same technology. Wireless devices may have somespecific capability(ies) depending on wireless device category and/orcapability(ies). A base station may comprise multiple sectors. When thisdisclosure refers to a base station communicating with a plurality ofwireless devices, this disclosure may refer to a subset of the totalwireless devices in a coverage area. This disclosure may refer to, forexample, a plurality of wireless devices of a given LTE or 5G releasewith a given capability and in a given sector of the base station. Theplurality of wireless devices in this disclosure may refer to a selectedplurality of wireless devices, and/or a subset of total wireless devicesin a coverage area which perform according to disclosed methods, and/orthe like. There may be a plurality of base stations or a plurality ofwireless devices in a coverage area that may not comply with thedisclosed methods, for example, because those wireless devices or basestations perform based on older releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” Similarly, any termthat ends with the suffix “(s)” is to be interpreted as “at least one”and “one or more.” In this disclosure, the term “may” is to beinterpreted as “may, for example.” In other words, the term “may” isindicative that the phrase following the term “may” is an example of oneof a multitude of suitable possibilities that may, or may not, beemployed to one or more of the various embodiments.

If A and B are sets and every element of A is also an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B={cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on”(or equally “based at least on”) is indicative that the phrase followingthe term “based on” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “in response to” (or equally “inresponse at least to”) is indicative that the phrase following thephrase “in response to” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “depending on” (or equally “depending atleast to”) is indicative that the phrase following the phrase “dependingon” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.The phrase “employing/using” (or equally “employing/using at least”) isindicative that the phrase following the phrase “employing/using” is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayalso refer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics ormay be used to implement certain actions in the device, whether thedevice is in an operational or non-operational state

In this disclosure, various embodiments are disclosed. Limitations,features, and/or elements from the disclosed example embodiments may becombined to create further embodiments within the scope of thedisclosure.

In this disclosure, parameters (or equally called, fields, orInformation elements: IEs) may comprise one or more information objects,and an information object may comprise one or more other objects. Forexample, if parameter (IE) N comprises parameter (IE) M, and parameter(IE) M comprises parameter (IE) K, and parameter (IE) K comprisesparameter (information element) J. Then, for example, N comprises K, andN comprises J. In an example embodiment, when one or more (or at leastone) message(s) comprise a plurality of parameters, it implies that aparameter in the plurality of parameters is in at least one of the oneor more messages, but does not have to be in each of the one or moremessages. In an example embodiment, when one or more (or at least one)message(s) indicate a value, event and/or condition, it implies that thevalue, event and/or condition is indicated by at least one of the one ormore messages, but does not have to be indicated by each of the one ormore messages.

Furthermore, many features presented above are described as beingoptional through the use of “may” or the use of parentheses. For thesake of brevity and legibility, the present disclosure does notexplicitly recite each and every permutation that may be obtained bychoosing from the set of optional features. However, the presentdisclosure is to be interpreted as explicitly disclosing all suchpermutations. For example, a system described as having three optionalfeatures may be embodied in seven different ways, namely with just oneof the three possible features, with any two of the three possiblefeatures or with all three of the three possible features.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an element thatperforms a defined function and has a defined interface to otherelements. The modules described in this disclosure may be implemented inhardware, software in combination with hardware, firmware, wetware (i.e.hardware with a biological element) or a combination thereof, all ofwhich may be behaviorally equivalent. For example, modules may beimplemented as a software routine written in a computer languageconfigured to be executed by a hardware machine (such as C, C++,Fortran, Java, Basic, Matlab or the like) or a modeling/simulationprogram such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript.Additionally, it may be possible to implement modules using physicalhardware that incorporates discrete or programmable analog, digitaland/or quantum hardware. Examples of programmable hardware comprise:computers, microcontrollers, microprocessors, application-specificintegrated circuits (ASICs); field programmable gate arrays (FPGAs); andcomplex programmable logic devices (CPLDs). Computers, microcontrollersand microprocessors are programmed using languages such as assembly, C,C++ or the like. FPGAs, ASICs and CPLDs are often programmed usinghardware description languages (HDL) such as VHSIC hardware descriptionlanguage (VHDL) or Verilog that configure connections between internalhardware modules with lesser functionality on a programmable device. Theabove mentioned technologies are often used in combination to achievethe result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the scope. In fact, after reading the abovedescription, it will be apparent to one skilled in the relevant art(s)how to implement alternative embodiments. Thus, the present embodimentsshould not be limited by any of the above described exemplaryembodiments.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112. Claims that do not expressly include the phrase “means for”or “step for” are not to be interpreted under 35 U.S.C. 112.

What is claimed is:
 1. A method comprising: receiving, by a base stationdistributed unit from a base station central unit, packet dataconvergence protocol (PDCP) packets of a radio bearer establishedbetween a wireless device and the base station central unit;transmitting, by the base station distributed unit to the wirelessdevice, the PDCP packets via a radio link; detecting, by the basestation distributed unit, a radio link outage of the radio link;transmitting, by the base station distributed unit to the base stationcentral unit, a first message comprising one or more parameters, whereinthe one or more parameters comprise: a first information elementindicating the radio link outage; and a cell identifier of a first cellassociated with the radio link outage; receiving, by the base stationdistributed unit from the base station central unit and in response tothe one or more parameters, a second message indicating a release of afirst wireless device context of the radio bearer; and releasing, by thebase station distributed unit, the first wireless device context inresponse to the second message.
 2. The method of claim 1, wherein theone or more parameters further comprise at least one of: a secondinformation element indicating that a number of downlink packetretransmissions reaches a threshold number of downlink packetretransmissions; a third information element indicating at least onefailure to receive a channel status information report from the wirelessdevice; a fourth information element indicating expiration of a timeduration without receiving at least one transport block from thewireless device; a fifth information element indicating at least onefailure to receive a precoding matrix indicator from the wirelessdevice; a sixth information element indicating at least on failure toreceive a rank indicator from the wireless device; or a seventhinformation element indicating a connection loss of the wireless device.3. The method of claim 1, wherein the base station central unitdetermines a radio link failure of the wireless device based on the oneor more parameters of the first message.
 4. The method of claim 1,further comprising transmitting, by the base station central unit to acore network entity, a third message indicating a release request for asecond wireless device context of the wireless device, wherein thesecond wireless device context comprises an interface connection betweenthe base station central unit and the core network entity for thewireless device.
 5. The method of claim 1, wherein the first wirelessdevice context comprises at least one of: a data radio bearer; a logicalchannel; a security configuration parameter; or an information parameterassociated with the wireless device.
 6. The method of claim 1, whereinthe second message comprises at least one of: a wireless deviceidentifier of the wireless device; or a first information elementindicating that a cause of the release of the first wireless devicecontext is a radio link failure of the wireless device.
 7. The method ofclaim 1, further comprising transmitting, by the base stationdistributed unit to the base station central unit, a third messageindicating completion of the release of the first wireless devicecontext.
 8. A base station distributed unit comprising: one or moreprocessors; and memory storing instructions that, when executed by theone or more processors, cause the base station distributed unit to:receive, from a base station central unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit; transmit, to the wirelessdevice, the PDCP packets via a radio link; detect a radio link outage ofthe radio link; transmit, to the base station central unit, a firstmessage comprising one or more parameters, wherein the one or moreparameters comprise: a first information element indicating the radiolink outage; and a cell identifier of a first cell associated with theradio link outage; receive, from the base station central unit and inresponse to the one or more parameters, a second message indicating arelease of a first wireless device context of the radio bearer; andrelease the first wireless device context in response to the secondmessage.
 9. The base station distributed unit of claim 8, wherein theone or more parameters further comprise at least one of: a secondinformation element indicating that a number of downlink packetretransmissions reaches a threshold number of downlink packetretransmissions; a third information element indicating at least onefailure to receive a channel status information report from the wirelessdevice; a fourth information element indicating expiration of a timeduration without receiving at least one transport block from thewireless device; a fifth information element indicating at least onefailure to receive a precoding matrix indicator from the wirelessdevice; a sixth information element indicating at least on failure toreceive a rank indicator from the wireless device; or a seventhinformation element indicating a connection loss of the wireless device.10. The base station distributed unit of claim 8, wherein the basestation central unit determines a radio link failure of the wirelessdevice based on the one or more parameters of the first message.
 11. Thebase station distributed unit of claim 8, wherein the base stationcentral unit transmits, to a core network entity, a third messageindicating a release request for a second wireless device context of thewireless device, wherein the second wireless device context comprises aninterface connection between the base station central unit and the corenetwork entity for the wireless device.
 12. The base station distributedunit of claim 8, wherein the first wireless device context comprises atleast one of: a data radio bearer; a logical channel; a securityconfiguration parameter; or an information parameter associated with thewireless device.
 13. The base station distributed unit of claim 8,wherein the second message comprises at least one of: a wireless deviceidentifier of the wireless device; or a first information elementindicating that a cause of the release of the first wireless devicecontext is a radio link failure of the wireless device.
 14. The basestation distributed unit of claim 8, wherein the instructions, whenexecuted by the one or more processors, further cause the base stationdistributed unit to transmit, to the base station central unit, a thirdmessage indicating completion of the release of the first wirelessdevice context.
 15. A method comprising: transmitting, by a base stationcentral unit to a base station distributed unit, packet data convergenceprotocol (PDCP) packets of a radio bearer established between a wirelessdevice and the base station central unit, wherein the base stationdistributed unit transmits the PDCP packets to the wireless device via aradio link; receiving, by the base station central unit from the basestation distributed unit, a first message comprising one or moreparameters, wherein the one or more parameters comprise: a firstinformation element indicating a radio link outage of the radio link;and a cell identifier of a first cell associated with the radio linkoutage; transmitting, by the base station central unit to the basestation distributed unit and in response to the one or more parameters,a second message indicating a release of a first wireless device contextof the radio bearer of the wireless device.
 16. The method of claim 15,further comprising releasing, by the base station distributed unit, thefirst wireless device context in response to the second message.
 17. Themethod of claim 15, wherein the one or more parameters further compriseat least one of: a second information element indicating that a numberof downlink packet retransmissions reaches a threshold number ofdownlink packet retransmissions; a third information element indicatingat least one failure to receive a channel status information report fromthe wireless device; a fourth information element indicating expirationof a time duration without receiving at least one transport block fromthe wireless device; a fifth information element indicating at least onefailure to receive a precoding matrix indicator from the wirelessdevice; a sixth information element indicating at least on failure toreceive a rank indicator from the wireless device; or a seventhinformation element indicating a connection loss of the wireless device.18. The method of claim 15, further comprising determining, by the basestation central unit, a radio link failure of the wireless device basedon the one or more parameters of the first message.
 19. The method ofclaim 15, further comprising transmitting, by the base station centralunit to a core network entity, a third message indicating a releaserequest for a second wireless device context of the wireless device,wherein the second wireless device context comprises an interfaceconnection between the base station central unit and the core networkentity for the wireless device.
 20. The method of claim 15, wherein thefirst wireless device context comprises at least one of: a data radiobearer; a logical channel; a security configuration parameter; or aninformation parameter associated with the wireless device.